About lords of thunder, i will try to go through the differences between them.
Sound effects for the sega version are either missing such as some of the sounds the bosses make, downgraded like the larger explosions or are ear splitting like some of the weapons after being fully powered up.
No need to talk about colors since thats probably the most obvious difference.
The sega version is missing a few things or details.
the dragon in 1st level does not kick up dust
rocks and torches explode into small piece's,
little dude in the water level cracks the floor open causing all the water to poor out,
fade in and fade out,
lightning in the forest level,
missing background layer/tiles in two areas,
The sega cd version does add a few things though, slow down and more parallax/line scrolling, the way they extended the line scroll all the way back for the water boss fight is realy cool.