In what sense, if any, can Concorde (and other jets) be said to have been propelled by the suction in front rather than the exhaust behind. Are they secretly the same thing? Is the question meaningless? Am I missing something terribly obvious?
To some extent, we could call the distinction meaningless because it's all one continuous movement in the intake, through the tube, and out the back. But there are a couple of technicalities along the way that we can also say make it significantly more suck than blow. (I'll get to what those two things are after a couple of paragraphs of setup.)
Near the back of the engine, right after the part where fuel gets added & ignited, there is a turbine. A turbine looks like a fan but works the opposite way: instead of using power to move a fluid, it gets spun by the movement of fluid, and thus draws power, which is used to drive the compressor at the front of the engine, which sucks air in & compresses it. In a plain turbojet engine, that's all there is to it, but other categories of turbine engines also use the power from the turbine to drive something else:
•Turboprop: the turbine's power drives a propeller (not a piston engine)
•Turborotor: the turbine's power drives a helicopter's rotor
•Turbofan: the turbine's power drives a big fan at the front of the engine
•Any type: the turbine's power might also drive a generator for onboard electricity, or not
Most of what we call jet engines are turbofans; the fan in question is what you can see easily at the front of passenger & cargo jet engines. In a turbofan, the engine core, where the compressor and turbine are and where ignition happens, is inside a larger second tube, called a bypass duct because the air going through it passes by the engine core. If you look at the back of a passenger or cargo jet engine, you can usually see the distinction between the core and the bypass; the protruding conical piece is the nozzle where air & burned fuel exit the core, and the gap around it between the cone and the outermost sleeve is the exit opening for the bypass, where air flows through & out without having ever been mixed with fuel. You can't see this distinction from the front because the drive fan covers both the core and the bypass duct, so it can pull air into both.
So, back to those two things that, I said before, make a jet engine's action more suck than blow:
1. The turbine draws energy by taking kinetic energy away from the post-ignition gases; they blow out the back slower than they would without a turbine present. Blocking & reducing that flow isn't something you'd want to do if that were your main source of thrust.
2. Where that kinetic energy is diverted to instead is the compressor, and a fan or propeller in a turbofan/turboprop engine, and thus the air that's moved by those things. That's where most of the thrust for that engine type comes from, and, since that's at the front of the engine instead of the back, the normal word for what they do would be sucking, not blowing.
Point #2 gets more important the bigger the bypass duct is. The airflow through the bypass duct divided by the airflow through the engine core is an engine's bypass ratio, so bypass ratio ends up as an indicator of how much more of the thrust is from sucking in at the front instead of blowing out the back. Higher bypass ratios are more efficient, but lower bypass ratios allow greater speed, so they get used on different kinds of planes. Of course, the ratio on a turbojet, as opposed to a turbofan, is zero by definition. Turbofan bypass ratios from about 0.3 to about 1½ ("low") are typical for fighter jets, and passenger & cargo jets' ratios are typically from about 3 up, with older ones generally lower than the latest ones, which have ended up in the 9-12 range, meaning only about a tenth to a thirteenth of the air they move ever gets fuel added! (I'm not even sure whether anybody in aviation today would call anything less than 7 or 8 a "high-bypass" engine anymore, but they would at least have been called that back when they were the newest & highest-bypass engines around.)
Concorde had turbojets, not turbofans, so point #2 was not an issue like it is for most jets now, but there was still point #1, the issue of deliberately diverting power from where it would blow to where it would suck instead. A new engine created for supersonic use today would be likely to be a low-bypass turbofan instead of a turbojet, just to use the bypass flow for core cooling.
). You must remember that at cruise speed, air is literally rammed into the intake of the engine. 
