Most bands on here that play the common Gothenburg influenced metalcore style are just labeled as metalcore. However, some are labeled as melodic metalcore. For example, As I Lay Dying is labeled as just metalcore while the very similar Miss May I is labeled as melodic metalcore. How should the labels be differentiated? Does it have to do with the fact that AILD's debut isn't Gothencore? It just sorta feels like there isn't that much of a difference between the two labels.

I'd say there's a bit of inconsistency with the labelling, yes, but "metalcore" is also a very wide genre that spans from bands that are pretty much melodeath with breakdowns (such as As I Lay Dying) to bands that are beatdown hardcore with heavier riffs (for instance, Gridiron), and everything in between. Defining the boundaries of where and when metalcore goes from just metalcore to "melodic metalcore" is a bit complicated due to the rather wide spectrum of sounds the genre can attain.

Many bands might have been added when the albums they had released were more of a rawer metalcore sound, so their genres weren't ever updated, while some other bands probably switch a lot between heavier and melodic riffing throughout their releases to tag them consistently as "melodic metalcore".

This being said, I'd argue bands like Killswitch Engage or As I Lay Dying could be labeled melodic metalcore, while bands such as Starkweather should keep the regular "metalcore" tag.

It's not just metalcore; there's a similar issue with power metal. Some bands like Kamelot are labeled here as "melodic power metal," which some might say is redundant regarding power metal. Sure, you could argue that "melodic" can separate softer bands like Sonata Arctica from the more abrasive ones like Blind Guardian, but those bands are already labeled as something like speed/power or thrash/power to indicate that they're more aggressive. There's also the issue that a band like Avantasia is not labeled as "melodic" either. I've made a thread about this, but I have yet to receive a response.

The "melodic" tag is redundant for metalcore and for power metal.

No, it is not for metalcore. Metalcore has different sounds and many of the bands that fall under this genre play a heavier style without so much melody. Sure, few of the bands within that style are on the site, but they exist regardless and they sound quite different than, say, Killswitch Engage.

Melodic power metal is probably redundant. Most power metal bands that aren't melodic are already tagged Power/Thrash or Power/Speed.

Metalcore is melodic, at least the acceptable more metal than core bands. The other bands you are referring to are not really metalcore but more like metallic hardcore or heavy hardcore with slight to no metal influence. Some of the metallic hardcore bands are still acceptable if they play more metal than hardcore, as an umbrella term they can still be labeled (understandably) as metalcore but their genre can be easily split to some metal genre/hardcore tag. I understand that the newer generation is not quite familiar with the labeling and it may look strange for them how things are labeled here but be sure that the majority of these bands are currently correctly labeled. With time things may change especially with the addition of new generation moderators, but for now tags are perfectly fine. A couple of years back half of the -core bands that get accepted today wouldn't even be considered for addition.