What is the relation between the EASA Light Aircraft Pilot Licences and the Private/Sailplane/Balloon Pilot Licences? The EASA licence and ratings requirements pages list:


PPL(A) - for aeroplanes
PPL(H) - for helicopters
SPL - for gliders
BPL - for balloons


which match:


LAPL(A) - for aeroplanes
LAPL(H) - for helicopters
LAPL(S) - for gliders
LAPL(B) - for balloons


It appears that you can upgrade an LAPL to its matching licence; for example, an LAPL(A) to a PPL(A) by taking further instruction and tests (except in the case of the sailplane licence, which seems not to require this, and the airship licence PPL(As), for which their exists no LAPL counterpart).

It looks like the LAPLs are generally easier to obtain (for example, requiring fewer flying hours). 

What's the purpose of this apparent duplication of licensing? Are the LAPLs intended to be a pathway to the other licenses, or a destination in themselves?
LAPL (Light Aircraft Pilot License) can be a pathway to a PPL (Privat Pilot License) but can also be just kept by it's own, as it's somewhat cheaper to get and maintain than a PPL.

LAPL has stricter limitations than the PPL, for example they are only valid in EASA countries and not in all ICAO states. Also, LAPL is limited to a maximum take-off weight (MTOW) of 2000kg and does not have the options of upgrading to IFR or similar (Night VFR is an option though) and a maximum of 4 people on board (3 passengers + you).

Therefore: If you are fine with the mentioned limits, you're good to go for an LAPL. If at some point you want to upgrade to PPL, thats not a big issue as it just requires the additional training hours (theory is the same for LAPL and PPL).