I've done/do both, so here it is...
English:
It's less structured, and less competitive. That said, the scores aren't scaled up. You do three areas of study - 'reading and responding', which is a text study, 'creating and presenting', in which you draw on the ideas presented in a context and 'language analysis', in which you look at how authors use language to persuade their audiences. You have a little more scope for your own interpreations (although this can be done in English Language if you put in the effort). There's a speech as an oral, but the rest of the SACs/exams are essays, so be prepared.
English Language:
Unit 1/2's a bludge from what I've heard, but I skipped it so I can't vouch for it. Unit 3 looks at how language represents identity and how it manipulates meaning - it's an essay writing unit, and you need to go out and research your own examples. Unit 4 is VERY dry - you look at how specific linguistic features facilitate conversations and deliver the meaning of written texts. It's interesting, but there's a lot of definitions.
I'm not sure what's easier to do well in - I think for either, if you're a good student, you can walk in and get anywhere between 40 and 50. But that's just my view.