They are two different nail systems, although they can both be used as a nno or sculpted on a tip or form. Gel is more flexible and suited better to hard nails whilst l&p is much harder and suited better to weaker more flexible nails. Both are great for protecting the natural nail if applied properly.
I have just trained in both systems and I have very hard nails, the l&p looked great but felt awful, my nails felt as though they didn't belong to me iykwim :lol:, I now have a full set of Brisa gel and they feel gorgeous, so much so that I am having them rebalanced and keeping them on for a while. If offering enhancements both systems have their own merits for individual clients but if I were you I would definitely look on the link given above and it will be worthwhile doing a search too hth xx