For instance: in ED, if you take damage you can fly to any station and repair it, cost about 19 credits for 1% damage in my Sidewinder (basic ship). In X3 Reunion, damage can cause components to fail, like the jump drive. Your speed will be affected (halved or more) meaning you can't run. Only a handful of stations in the galaxy ("shipyards") do repairs. And when you get there: the repair cost is the replacement cost. To repair 1% damage, it costs 1% of the purchase cost. Considering you start off with a 400K credit ship, and 5K credits in cash, that's a major problem. Took me several days of gameplay before I could repair a badly damaged ship from one of the stroryline missions. ED is a cakewalk by comparison - though I have to admit, I really grew to like the difficulty of Reunion. It's a bit refreshing
I've only briefly played the others, Terran Conflict, Albion Prelude and the latest, Rebirth. I still think ED could appropriate some ideas from that series though. I am finding the ED gameplay a little bit empty.
Components getting damage can cause them to fail. I have had my thrusters malfunction, etc and eventually fail( leading me to self-destruct) after enough damage.
And not all stations can repair your ship as well. The major stations can, but not all the outpost stations. At most the outpost stations that can't repair your ship can only replenish your oxygen.