They are very different. Tolkien's was basically compiled by his son from his lecture notes, I believe. It was meant for his students to help them learn Old English and probably would not be what Tolkien would have published as an official translation had he been alive. That said, it is beautiful and I prefer it to Heaney's. Heaney's is a verse translation and has the benefit of having the original language next to the english as well as quick plot notes on the margins to help find what you're looking for at a glance.
What was it like to read the two different Beowulf translations?
They are very different. Tolkien's was basically compiled by his son from his lecture notes, I believe. It was meant for his students to help them learn Old English and probably would not be what Tolkien would have published as an official translation had he been alive. That said, it is beautiful and I prefer it to Heaney's. Heaney's is a verse translation and has the benefit of having the original language next to the english as well as quick plot notes on the margins to help find what you're looking for at a glance.
Tolkien wanted to capture the feeling and spirit of the original poem.