Now now, guys, calm down.
It is strange to hear a lot of the things that Castlevania IV is usually praised for, being neglected. Abnormal Freak has pointed out some wonderful examples of how Super Castlevania IV has improved the formula from the NES days.
I mean, just with controlled jumps alone...
But anyway, I think we should probably try to take a look at this in a more objective manner. Both the games are great now, and were great at the time they came out. But let's try to analyze things here:
EXAMINATION
Super Castlevania IV VS. Castlevania Bloodlines:
Graphics:
Super Castlevania IV
CV4 offers a very high color palette, provided for by the SNES graphics chip. It also offers a number of effects that were not available at the NES days, such as the Mode7 Rotating Room and Spinning Corridor. It also allowed for relatively large graphics to take over the screen, as well as multiple layers of graphics and animation. The 'style uses a mix of reds, purples, and browns, as well as some peppering of 'dithering' with its tile graphics, to create a very gritty, dirty feel to the objects.
Castlevania Bloodlines
Bloodlines offers a very high-contrast color palette, provided by the Sega Genesis graphic chip. Because of the color limitations, the palette is not as rich as the SNES palette, but the usage of it is very well-varied, as showcased on the radically different levels at times. The game, unlike CV4, uses very bright colors for its tiles, and also uses a very 'clean' look to it stylization of most platforms. That is, most of the platforms in the game have a very 'rectangular' sharp feel to them. Bloodlines also offers some interesting effects not done before, such as the moving reflections of the Atlantis Shrine (stage 2), the tilting of the tower in the Pisa stage, and the 'snaking' platforms of the same stage (to simulate a tall cylinder).
Sound:
Super Castlevania IV
We're really not going to talk much about the compositions themselves (topics about this have already been discussed for ages). However, we will talk of the amount of different, varied tunes, how they fit into the large amount of stages, and about the quality of such tunes. CV4 has a distinct 'baroque' feel to a lot of its tunes, which lends a distinct consistency to its arrangement that lends to some cohesiveness to the soundtrack, as opposed to titles like Symphony of the Night, which have awesome tunes that are so disparate from one another that sometimes lead one to question 'why?'. The instrumentation given the SNES sound chip is also worth mentioning, as the bassoon sounds like a bassoon, the strings like strings, and the percussion as such. It's worth mentioning.
Bloodlines
Bloodlines as amazing composition, which is shown by the fact that the titles are popular even today. What suffers greatly, however, is the sound quality. This is not because of Konami, but because of the Sega Genesis's sound chip, which at best, can only provide us with high-quality FM-Synthesis sounds. So, while the composition is great, the instrumentation is really not. We are fortunate that the instrument choices for most of the stages are very good. The Ruins of Castlevania, the Atlantis Shrine, Munitions Factory, and Castle Proserpina have some of the greatest tunes, but the Tower of Pisa and the Palace of Versailles tunes suffer because of the genesis's "Byooooooooooiiiaaaaanggggg" bass sounds and grating trebles. The percussion, especially the Toms, sounds a bit off-putting. This is not music that you can pop into your media player and do some easy-listening to, as at times your ears may argue with you.
Play Control
Super Castlevania IV
CV4 has, quite possibly, the most refined play control of any ClassicVania title. As it was pointed out before, it was the first CV that truly did controlled jumps on the main character (Grant in CV3 doesn't quite count as he's not the main character). The ability to whip in multiple directions, and the ability to use a subweapon with one button instead of the classic UP+ATK is a worthwhile addition. You can also use Subweapons in the middle of whip-swinging because of the R button (you can throw axes/crosses while stuck to a ring with Simon's other hand). Enemy placement is also well-regulated. The enemy locations make sense most of the time, and there's never truly a moment of cheapness (except, maybe, in the dungeon level with the disappearing platforms, or if you mistime a jump in the final crumblingstairs tower).
Castlevania Bloodlines
Bloodlines returns back to a more 'classic' style of gameplay. John and Eric jump in only two directions, straight up, and forward. There are no controlled jumps in this game. Some people may argue that this is a disadvantage, while others will say that it makes for a more controlled, strategic style of gameplay where decision-making is involved when making jumps. Whatever the case, this is what they decided to go with. We've got two characters instead of one, and we've got a number of other moves that have been added to the arsenal. While WhipSwinging still exists with John, there are only a few instances where it's really put to use (you can 'latch' on to any ceiling platform and you're invincible and become a weapon when swinging). Multidirectional swinging exists with John, but it's less directions than Simon. The Subweapons also use a different button, and can be "Crashed" with UP+SubWpn if you have enough Jewels. You can also powerup your whip/spear to a flaming ultimate level that lasts until you get hit. That is pretty spiffy.
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I have to talk about the big elephant in the room, though... that elephant is Release Time.
While one can argue that the Bloodlines and Cv4 have just about enough positive points to be counted as Equal... Super Castlevania IV is a release title for the SNES. This means that when the console was new, there was so much innovation with all the aforementioned aspects, that it's an explosion of a breakthrough. At release time, CV4 created a big splash with its innovations on the Castlevania formula. Bloodlines was released much later, with Rondo of Blood on the PCEngine coming out first (I believe). This means that the developers of Bloodlines had ample time to work out all of the obstacles that the Sega Genesis's hardware would have posed... and yet the game did not generate nearly as big of a splash. It is a solid, noteworthy title, but for the time it came out they really could have worked on it more. It feels as if it was just done to add another console style game, or to appease fans of that system. At least, that's what it feels like, to me.
You have two very good titles, but one was released much earlier than the other and it's just about as good (and most people will argue here that it's better in every way) than the other, while the other does not feature enough changes and improvements given the huge time window between the two titles.
Anyway, I hope that my little post here generates further discussion, and I hope it helps the original poster with his project with the other forum. Please feel free to discuss.