It is usually PU or PVC material. I saw a few pictures of Mushroom leather and Pineapple leather by Pinatex which (to me) looked same as the real deal. Other terms I've noticed (not 100% so do your research) are Lorica, Pleather, Patent Leather, Faux leather, Protein Leather, Artificial leather and Man-made materials etc.,
Lorica looks very nice for watch straps and I intend to order a few in few months. Cork seems to be a good alternative for wallets and belts.
Also, I discovered recently that glue used in manufacturing shoe can be derived of animal products. So, unless the seller claims that it is vegan and you trust them, even if you buy pure PU leather, you still can't be sure if its vegan.
P.S: (rant mode on) I understand that vegan products are a niche market, however, pricing vegan products 2x+ over the genuine leather ones is very discouraging. From what I understand, vegan materials don't cost as much as genuine leather. I'm not sure why these exclusive vegan brands charge a premium. It will certainly discourage people considering the lifestyle. I wonder, when the vegan-exclusive brands align their business priorities with the core ethics of veganism and price the products reasonably instead of charging a premium. A certain amount is ok, I think, to encourage them to keep supplying but hey who am I to decide what is OK and what is NOT. Just a thought!