There are not a lot of major differences between MT4 and TradeStation, functionally speaking. MT4 is more visually appealing and if you are one that likes to use or experiment with indicators then MT4 is definitely the platform to use. All in all it is a much more versatile platform than TS.
TS is great if you like to keep things simple. Basic indicators are available but unique/custom indicators are much more limited compared to MT4 (generally, only available from Codebase because TS uses lua for programming). Trading from the screen is a bit easier with TS. Moving stops and limits with the mouse is as simple as it gets. The learning curve is very small. Anything more complicated then TS starts to get a bit clunky.
I’ve used both and there just isn’t a great deal of difference between the two unless you like to use indicators. I don’t so I slightly favor TS. But if you like to monkey around with the latest, greatest indicators out there then MT4 wins, hands down.