I did both. I'm taking my A2s at the moment, with AQA as my exam board for History and Edexcel for English. Funnily enough, I'm hoping to study English and History at university next year!
Workload - personally, I found History to require a lot more work.
Essay Writing - I think History essays are harder to write. English essays are longer though. (my exam for History is 2 45 mark essays and for English it's a 40 mark essay and a 60 mark essay).
Difficulty - I definitely found History harder, and it reflected in the fact that it's probably my weakest subject. I enjoy History, but I found the units for this year absolutely mind-numbing. History also requires a lot of memorisation of key dates/policies/etc, as well as historians' quotes. I wrote most of my English coursework in the few days before it was due and got 79/80, whereas I was working on my History coursework for weeks and got about 38/60 if I remember correctly.
Interesting-ness - depends. In English, I've studied A Clockwork Orange, Brighton Rock, Othello, A Streetcar Named Desire and The Great Gatsby, and I've loved those books/plays, whereas other people in my class have hated them. Same applies to History - it all depends on what YOU find interesting.
Fun-ness - same as above. Also depends on the teachers you have - my English teacher is so passionate about his subject and it shows, whereas the History teacher I had last year would tell us to make notes from the textbook for the lesson. If the teacher enjoys teaching, then it makes the lesson a lot more fun.
Grade Boundaries - not too sure, but I think they're about the same. A difference between an A and a C is about 20 marks, although I recall getting about 70% in a past paper and my teacher gave me a high B/low A. I think History is a bit more unforgiving.