Almost & nearly

1 meaning: progress, measurement and counting

Almost and nearly can both express ideas connected with progress, measurement or counting. Nearly is less common in American English.

I've almost/nearly finished.

There were almost/nearly a thousand people there. Sometimes almost is a little 'nearer' than nearly. Compare:

It's nearly ten o'clock. (= perhaps 9.45)

It's almost ten o'clock. (= perhaps 9.57) Very and pretty can be used with nearly but not almost.

I've very/pretty nearly finished, (not .. .very almost...)

2 other ideas

Nearly mostly suggests progress towards a goal or closeness to a figure. We prefer almost for other ideas like 'similar to, but not exactly the same', and to make statements less definite. Jake is almost like a father to me. Our cat understands everything- he's almost human.

(not ... he's nearly human.) My aunt's got a strange accent. She almost sounds foreign.

(not ... She nearly sounds foreign.)

I almost wish I'd stayed at home, (not I nearly wish...)

3 negative words

We do not usually use nearly before negative or non-assertive words: never, nobody, nothing, any etc. Instead, we use almost, or we use hardly with ever, anybody, anything etc.

She's almost never I hardly ever at home, (not ... nearly never...)

Almost nobody I hardly anybody was there.

He eats almost anything.