Normal Engine:
Your normal, off the shelf, sub-light engine. Moves your ship at a max. speed as stated in the design(F5) or ship (F6) window.
Edit: Normal engines come in four flavours:
Military: Small, good power to weight ratio. Ships mounting military engines may not be taken through a jumppoint by a jumpship using a civillian jump engine
Civillian: Large, bad power to weight ratio, very fuel efficient. Ships mounting civillian engines may not be taken through a jumppoint by a jumpship using a military jump engine
FAC: Miniaturized military engine. Great power to weight ratio. Fuel hogs. Ships can only mount 1 of those
Fighter: Even more miniaturzied. Incredible power to weight ratio. Fuel hogs on steroids. Ships can only mount 1 of those
Hyper Engine:
Doubles the mass of your normal engine (this penalty can be lowered by tech). Moves your ship at 10x the max speed of normal engines.
WARNING: Only works outside the Hyper Limit (on the system map (F3), Display, there is a checkox (lowest) Hyper Limit, checking this, shows it. For the solar system, the Hyper limit is just outside the Neptun path.
For single star systems, Hyper Engines are rarely usefull, as most of the system is inside the limit anyway. Useful for moving from one component to another in a multi-star-system (Less so, since Steve introduced Lagrange-Point-In-System-Jumps). Personally, I never use them, as they kill Power to Mass ratios.
Jumpengine:
Not an engine at all, actually. Used to open a jumppoint (think Babylon 5), in order to move a ship/ships from one solar system to another.
Ships with jump engines can take a number of ships with them through a jump point (number depends on tech researched, starting tech is 3, i.e. the jumpship plus 2 others). The other limit is, no ship can have a larger mass than either the jumpship, or the rating of the jumpengine THE LOWER OF THE TWO APPLY i.e. if you put a 20.000t jumpengine on a 5.000t ship, the largest ship to go through the jumppoint is a 5.000t ship.
Edit: Jump Engines come in two flavors, Military and Civillian
Military: Carry ships with military engines through jumppoints. Small. Can be vastely improved (carry more ships through, appear further away from the jumppoint) by tech.
Civillian: Carry ships with commercial engines through jumppoints. Large. Can only carry 1 additional ship through a jumppoint
Jump Gate:
Build on a jumppoint. Used to let ships without a jump engine enter a jumppoint (again, think Babylon 5). WARNING: Works for your enemy too! You don´t "own" a jump gate, everyone can use it, no matter who build it originaly.
This is the main drawback in my book: If you (or your enemy) has, say, 3 jumpships, that each can bring 2 other ships along, the first attack wave can mostly be those 3 jumpships plus 6 other combat ships. If you have a jump gate in place, a fleet of 50 ships or more might suddenly appear on a nice sunday morning (think Pearl Harbour on steroids)
Civillians will only use jump gates to go to other systems (at least this used to be true, not sure if this was changed recently)
