One looks like the sun.
One looks like the moon.
Gasps. Oh wait there's more.
Lunatone's Special stats are higher: Lunatone's stats
Solrock's Physical stats are higher: Solrock's stats
Lunatone learns Hypnosis, Future Sight and Magic Room; some different TMs & move tutors as well: Lunatone's learnset
Solrock learns Fire Spin, Solarbeam and Wonder Room; some different TMs as well & move tutors as well: Solrock's learnset