I agree with this. Each platform can be completely different. Banks often have their own internal platforms too. Some are even set to trade in millions by default. So when you enter an order for 15 shares, you're really buy 15 million shares and so on.
Text based systems: FBSI, SIS
GUI based systems (when not pointing and clicking): Patsystems JTrader<A>, Trading Technologies' XTrader<A>
<A> These are systems I have used for personal use but not at work