konami titles

Some games get different titles in different territories (not just related to being on MSX). Sometimes the games themselves are also different to varying degrees. There's not going to be one single answer for this.

Vampire Killer's release was overseen by a Japanese Manager who was in Konami UK back in the day. So bad localization for the title would be the least likely in that case. Vampire Killer's name refers to the name of the whip. Perhaps market research pointed out that that name worked better in Europe/ for msx at that time. Castlevania was released later with that title for NES. So perhaps other team/ new insights etc determined the new name. Perhaps because it was on another platform they wanted to give it another name or whatever reason.

With Gradius I think I have read somewhere way back that they couldn't register Gradius as a trademark over here or vice versa.

Life force is a different game from salamander. It is similar but the levels have a more biological ambiance like you are inside some huge alien entity or living planet or something. The Japanese salamander for nes is different from the American title.

Green beret refers to British special forces. Probably that speaks more to the imagination of English/ European gamers. "Russian attack" might possibly have been a more interesting title for American public because it refers to the Russians as the antagonists (like many movies did too during the cold war era).

Goemon is a completely different game even though the nes and msx version have the same title and subtitle. Probably there was far less collaboration between the famicom and MSX teams than for instance with Akumajou Dracula. If you look at the credits for the msx version (since the famicom version only has made up names) you can see that there are quite a few people who later on also worked on other famicom games. And perhaps they started at the same time with the same project, diverging early on. With Akumajou Dracula the MSX team started off first and had a head start. Then the FDS project was started and was released just a few days earlier than then msx one. Goemon for NES is less big by the way. It only has 6 provinces as opposed to the 7 of the MSX version. After the loop on NES the stages are basically the same iirc. They might only be slightly more difficult. On MSX they are different.

Like Boblet already said there are probably many (business) reasons why games are called differently on NES and MSX. In many cases even if main titles were the same, subtitles were different. And in some cases even the game types were different like with king kong2 and hinotori.

And as always: the Japanese title is the original name. But that doesn't always work well in other countries.

Samor: I don't think Spirit of F1 is an actual spelling correction but it is a less ambiguous title than F-1 spirit is. The US name World Circuit series might be because they just couldn't get the rights to use F1 in the name from FIA (was it FIA back then?). And indeed it is a very bad title.

I don't know about all game release dates but I do know that gradius 2 was released first on MSX. Vampire Killer could have been because it was worked on first but the FDS version was released first. No real wonder since many levels are vastly simplified. Level 2,4 are much shorter. Level 8, 9, 10 are simplified. Level 11 is basically one stretch of dropping fleamen. In level 15 they were even too lame to place paintings inside the frames. Level 16-18 are severely reduced too, with level 18 only being the boss. Perhaps his second form is better though.

Besides that the game mechanics in castlevania are much simpler with no traders, no warps, no keys to find, no special items (unless you count the II as a special item). The only unique mechanic is that you can uncover some treasure items by standing in certain places. Just the fact that there is something of an end demo, the background map in between level sets and possibly the scrolling are better elements to castlevania.

Metal gear also seems a vast simplification: only 1 screen alarms and cameras which don't see you if you hug the wall; greatly reducing the need to sneak. Enemies have less challenging paths & positioning. No battle for the silencer, no hind, music is far blander and more repetitive, walls that can be simply knocked down. Maps that have been simplified or artificially spread across buildings. Being able to skip certain parts and that dying and continuing is a valid shortcut in the game. The guys with jetpacks on their backs don't even fly. It a;so has a lame trick with the transceiver to remove pitfalls but that might be equally lame as the trick to nullify damage from electric floors. Probably a lot more can be said. The msx versions are indeed more appealing in many ways to me at least.

Your link to metal gear in nes version almost makes me wonder why nobody tried to make a castlevania in msx version.

I was thinking about more than the title screen but that is cool too.

I think salesmen hidden in rocks are weird though. Slapping them to make them sell things to you is even weirder, but that's video game logic at its best ;-)
Also, for some strange reason the slamming castle doors are replaced with hypermodern electronic ones (complete with buzzing sound).