By instruments do you mean the sound loops or the synthesisers.
If its the sound loops then MM comes with a basic set of loops to get you going ... to add more you can buy soundpool collections on disc or as download from catooh.
If its the synthesisers - these are built in to MM, the demo doesn't have them all MM16 has vita, livid, robota, beatbox 2, drum n base, atmos. MM16 Premium has all of the above plus Revolta 2 and more Vita instruments.
You can also add VST instruments yourself - lots available for free on the www.