Hi, welcome to GoY, at this stage I doubt if you can tell the difference, but I don't grow veg, so maybe someone will be able to tell you, when you start to get flowers, you may be able to distinguish which is which, if not, try posting a photograph on here and ask again, Derek.

Very difficult, last year I bought a courgette plant from the garden centre, with the right label, and it turned out to be squash, the labels get muddled, I didn't realise until it was quite big by which time it was to late, so really you take a chance.

I don't grow veg but I seem to recall that courgette leaves have a spikey edge to their leaves - dentate - lots of little teeth! If that helps.