the main link between The Lord of the Rings and the Kalevala is Tom Bombadil and the poetic style of his speach which is more evident in "The Adventures of Tom Bombadil" (note Turin appears in the silmarillion which can be considered to pilfer from the bible with that whole tedious creation myth which makes the beginning hard to get through). The main difference might be considered to be the lack of christian references in the lord of the rings since it was written from scratch and not corrupted over the years by do gooding purveyors of middle eastern mythology. See the mabinogion for similar corruption by the church.
Another consideration is that its an epic poem so not so easy to read