VorTech pump: MP10, MP20, MP40 (what size for 90gal)

you dont need that for freshwater. most if not everyone use that for saltwater.
you can just get a koralia pump if you need more flow. it is alot cheaper


as for the difference, the eco smart if the new driver for the wavemaker
plus they discontinued the MP20. the MP40 is the replacement

The Ecosmart is a cool feature which allows two powerheads to work together and wirelessly using a single driver. Generally vortech kit is used in reef tanks but there is nothing wrong with using in a fresh water tank as they are high quality, reliable and have adjustable flow rates. Ive got an mp10es in my 40g plantedtank and it gives me great flow around all plants and gives a very natural & gentle swaying motion to plants.

You'll have less stuff in the tank with the Vortech as opposed to the Koralia also.