The JAA/EASA PPL is 45 hours which may include flight tests.
The NPPL is a minimum of 32 hours PLUS two tests which will bring the minimum hours up to nearer 35 hours. Most though will still do the same number of hours as the JAA PPL to complete, that is 50 - 65 hours. The written exams are the same.
Microlite is 25 hours but my Microlite instructor friends tell me that most microliters usually take in excess of fifty hours of flight training.
Looking at advertised prices the Microlite costs are 15-20% cheaper, at the very best, than the PPL/NPPL. You then have to purchase a Microlite, so be ready to fork out anything between £15 - 45 grand for something new. Shares are available of course, but not such a good deal really.
I took my nppl m, & only took ONE test, ( GST ) + the usual exams, so where you get TWO from I don't know !
+ a modern 3 axis microlights, will out perform most ancient american pump engined machines, at a fraction of the cost, ( to buy / rent / maintain / run )oh and there very very quite, so you don't annoy anyone