There the same mutants, just a darker & different shade of yellow it looks like. height though.....maybe there the midgets of the super mutants.

The Behemoth is undersized for a "behemoth" but the rest seem appropriately sized for Super Mutants

The size of the Super Mutant Behemoths in Fallout 3 was a bug. Even Bethesda stated that they didn't intend Behemoths to be that big (just look at the size of the fire hydrant they wield), but a bug shipped with the game that caused them to be that big, and they chose not to fix it. Kind of like how in Skyrim the Giants being able to launch you into space was an unintended bug, but Bethesda decided not to fix it because it was hilarious.

The behemoth in FO3 was scaled up, said the devs, hence the illogically-sized hydrant and car door...
The behemoth in FO4 is the correct size...

From the Fallout Wikia:

Its theorised that mirelurk kings arent even the same species has mirelurks instead its like a symbiosis relationship which I find really interesting.

The Kings in Freeside are undercover Mirelurks confirmed?

Just a new style. Wish we'd gotten to see more of them though.

Also, I don't know if I'm allowed to post this but here is the guy who made the new super mutants http://www.twitch.tv/jonahlobe

He also made the Deathclaws if I remember correctly, as well as the mirelurks. He doesn't work there anymore though.

He's always happy to answer any questions, so if you're interested in this kind of stuff you should go watch him when he streams.

If this isn't allowed then I'll just remove the post and I'm sorry in advance.

Wherever they're from, I just hope there's not as flipping many as there was in FO3. There were so many you'd think they weren't sterile.

There's only one strain of FEV. The super mutants of the east coast "mutated" for a gimmick, you know, to give the teenagers the "super mutants experience". It would be more lore friendly thinking the east supermutants as overgrown raiders that painted themselves with green paint.

No offense, but I am one of those teenagers that grew up with that horribly painted raiders -w-' (yes I'm still young)

Not true at all, the FEV used by the enclave to try to kill everyone in fo2 was different from the one that made super mutants in Fo1.

Thats what makes it a second strain and not the same strain. You might disagree with the resullts in FO3 but still said it's caused by that strain of the FEV. Like Spannish flu, while still flu isn't the same as bird flu.

From what I recall reading the Vault 87 terminal entries, it's implied that FEV research in Vault 87 was happening separately from what was happening at Mariposa. The FEV developed in Vault 87 had some key differences, like worse cognitive damage, the yellow tint, and the indeterminate growth.

They have just made them look more realistic, if the premise of a super mutant or in fact any of the game (aside from nuclear war and survival) can even be considered realistic in the first place. Everything is more to scale and the colours are no longer horrible.

i think theyre just the vault 87 super mutants just restyled so they dont look like there skin is made of rancid pizza toppings.

I'm more concerned about the apparent size change than the new color. I remember the first time I stumbled upon a group of Super Mutants in F3. I wandered into what I thought was a raider camp under the cover of darkness, I turned the corner and about 30 feet away I see this towering yellow green monster holding a giant club and charging towards me. It was a really impactful moment for me personally because being new to the series I wasn't expecting them and their size made them very intimidating. They appear from the trailer to not be much larger than normal humans and that kind of bummed me out. I liked them as towering mountains of muscle not palete swapped raiders. Even the new behemoth only seems slightly larger than our old normal super mutant.

Sorry repeat post please delete

Personally, I'm one who's not amazed by the amount of color in 4 compared to 3 and New Vegas. It was something about the Gray/Brown washed atmosphere, the colors made the game more immersive and added to the gritty tone of the games, but from the reveal at E3 we've seen areas where the new colors weren't as vibrant so I'm satisfied. it's going to take a day or two to love the new coloring.