These words get used loosely in broker threads. Working definitions, with corrections welcome:
Stop level: how close to the market you're allowed to put a stop, limit or pending order. If it's 30 points on a 5-digit quote, you can't put a stop closer than 3 pips.
Freeze level: the distance from an order's trigger price inside which you can't modify or delete it. Close to the trigger, the order is locked.
Raw account: a marketing term for low spread plus a separate commission. Not a regulated definition.
ECN: originally a specific type of electronic network matching orders between participants. In retail FX it often just means orders are passed to liquidity providers, and its meaning varies between brokers.
Both levels are visible in MT5 in the symbol specification, and an EA can read them through SymbolInfoInteger (the freeze and stops level properties). Many raw accounts show 0 for both on majors, but some brokers raise them around news, and the specification only shows the current value.
A practical tip: an EA should read both values before every order modification, not once at start-up.
Good list. One thing I would add for newcomers is the difference between the stop level and the spread when placing pending orders, because I made that mistake myself. I tried placing a buy stop 2 pips above the market on a pair where the stop level was 20 points and it kept getting rejected with an invalid stops error, and it took me an hour to understand why.
Also worth mentioning is that the freeze level can bite during trade management, not just entries. I had an EA that tried to move a take profit when price was just a few points from it, and the modification failed every time. It looked like a bug in my code. After adding a check on the freeze level before each modify call, the errors disappeared.
On ECN, I have seen brokers label an account ECN while the orders were clearly executed against their own book, with last look on fills. So I judge an account by its actual execution statistics, like the slippage on stop orders and the commission per lot, rather than by the name on it.
