L&P is what is generally referred to as 'acrylic', in actual fact all three systems are acrylic based, and in this case l&p stands for 'liquid' and 'powder', because that's what you're mixing together.
Don't feel stupid for not knowing, I didn't either, and it seems like a lot of nail techs don't if their menus round me are anything to go by. That said, it's just as likely that they put 'acrylic' down because that's what people are used to calling it.
I'm currently learning l&p, I did my two-day beginner's course with Odyssey, and it's harder than you think it will be. I, too, chose it first because I thought it would be the hardest, and if I could master that I would pick up the others a bit easier. I have to be honest and say that I am looking at doing my gel and fibreglass courses pretty soon as I'm finding l&p difficult. I don't mean to say I'm giving up on l&p by any means, but if I can master the others a bit faster I would rather offer my clients gel or fibreglass for now and practise the l&p in my own time than get a bad rep by offering l&p enhancements I'm not happy with. It may turn out that I master them all in the same timescale, who knows? As yet I haven't opened myself up for business so I'll see how it goes.
Which to go with first is up to you - if you only intend offering one system for now then it's probably a good idea to do some market research in your particular area and see which is most popular. If you intend learning all three, or at least two, then I'd probably say start with the harder one! For all my griping, I know it's better that I'm pushing myself with the l&p. In the long run it's probably best to do at least two systems to get a decent client base, but that's up to you and how cash flow goes. I know from having spent over £1000 in the last two months, and a lot of them on silly un-thought-out purchases, that it's best to research first.
And this is probably the best place for it!
Welcome to the site. Lol x