I think it's just in the same key. It uses a few of the same chords, (naturally, since a key is a set of chords/notes) and the rhythm of the songs are very similar. Kind of like dun...dun...dun...dundundun. Also, at about 2 min in Jim's it does a similar change in dynamics (volume/intensity).
It doesn't take much for songs to sound similar, just like a similarly-shaped chin and nose can make two people look "alike".