I've flown most of the common light and microlight aeroplane types, as well as quite a few more obscure ones.
The first big difference is engine handling. The common microlight engines (I've flown Rotax 2 and 4 stroke, Jabiru, Fuji and JPX) universally have chokes, and very seldom have mixture controls, they also usually operate at quite high RPMs and require gearboxes. They are usually (not always to be fair) very well instrumented. Common light aeroplane engines (I've flown the main Lycoming, Contininental and Franklin models for example) have mixture controls, do not use a choke for starting, and probably are not as well instrumented as microlight engines. To be honest, the microlight engines don't need so much instrumentation, but most microlight designers have a lot of hours flying 2-stroke engines, so are paranoid and want to monitor everything.
Shut a light aeroplane engine down on the mixture, a microlight engine down on the ignition.
The handful of microlight engines with variable pitch props generally use "coarse/fine" electrical pitch mechanisms, rather than constant speed mechanisms. Most of the slightly larger number of light aeroplanes using variable pitch props use constant speed devices, with hydraulic controls.
Microlights have a lower stall speed generally, and a low mass. This means that at landing they have relatively low inertia and often it's necessary to hold a larger margin above the stall on final approach than you would in a light aeroplane, and because of the high induced drag in the roundout and flare, the roundout height tends to be much lower than in most light aeroplanes.
The low inertia, low stall speed, and fairly good power:weight of a microlight usually leads to quite short take-off roll, and very short take-off time compared to most light aeroplanes. This can take quite a lot of getting used to when switching between the two.
Microlight cockpits tend to be much simpler than most light aeroplane cockpits - there are unlikely to be any navaids beyond a compass and GPS: expect no AI, VOR, ADF, DME, DI. Expect only a single altimeter. Instrument panels tend to be much lower than the majority of light aeroplanes, giving a far better view forward, but also quite different flying attitudes. Radios are usually handhelds mounted somewhere and patched into a simple intercom. Light aeroplanes by comparison will normally have built in radios, intercoms, and a selection of navaids - as well often as a second altimeter, gyro-DI and artificial horizon, these make the task of cockpit management in a light aeroplane generally more onerous. Many modern microlights have LCD based "glass cockpits".
Light aeroplane cockpits are very standardised - 3x2 standard primary instrument layout, engine instruments below or to the right of that, engine controls bottom centre of the instrument panel. Microlights vary a lot more.
Printed checklists seldom exist for microlights - microlight pilots are taught to do their checks from standard mnemonics. It works. Light aeroplanes normally come with printed checklists, and also usually require fairly elaborate pre-flight navaid checks that will be alien to most microlight pilots.
Most light aeroplanes have a pair of yokes, or occasionally a pair of sticks. Virtually no microlights use yokes, and many have a single shared stick between the seats.
Virtually all light aeroplanes have flaps, many older design microlights don't. Virtually no microlights have electric flaps, the CT family being the obvious exception.
Many microlights have significant errors in the ASI, whilst most light aeroplanes should be within 5% from about 1.1Vs up to Vne.
Most microlights and light aeroplanes shouldn't be deliberately spun. If you do get into that unhappy position however, the recoveries are generally different. For a light aeroplane expect throttle closed / back stick / opposite rudder / stick forward, for a microlight expect throttle closed / centralise all controls.
Fuel planning in microlights is different - gauges tend to be much more accurate, but also the aeroplanes are much more effected by the wind. So, planning tends to be much more fluid and continuous than the pre-flight with occasional checks that you do in a light aeroplane.
Most microlights have 4 point harnesses, most light aeroplanes 3 point.
Microlights tend to be much more affected by turbulence than most light aeroplanes are - to the point that on a gusty day it's common to take ballast!
What's the same?
- Sense of the controls
- Full dual controls (usually, many light aeroplanes don't have brakes on the right)
- The importance of learning to fly the right speeds and attitudes FOR THAT AEROPLANE.
- The requirements for good airmanship.
- Both are tremendous fun, and all flying is good.
I may come back and edit this post later when I think of other stuff to say.
G