The PPL includes the permission to fly "generic" single-engined piston-powered (SEP) planes such as the C152, C172, PA28 to name but the most widespread. As said, this includes two-seaters, four-seaters, and a few planes with 5 or 6 seats. A PPL can be extended with privileges like night flying and instrument flying. It is also the first step towards type ratings for more complex planes, including but not limited to twins.
Microlights OTOH can never have more than two seats and are limited to day-time VFR flying.
They make up for these limitations with lower cost of acquisition, operation, and maintenance. No to mention a less stringent medical inspection.
It really depends on what you are ultimately going or hoping to do.