Rare Groove has a unique sound (80's stuff I mean), that is why its called Rare Groove. Another thing, Garage evolved from House Music with a different sound and bass to it, called H & G. Later the Music style changed from it's US counterpart making it UK Garage. Grime now is basicially the real 'dark' version of UK Garage with a Hip Hop and Ragga/Dancehall kind of lyric element to it. Grime can not be just like Hip Hop because of the tunes used and speed of the bpm as well.