How these work?...smps

Hi guys,
How do i ask this without sounding newbe?Well i am when it comes to power supplies!
I need a general concept of how Offline full-bridge SMPS/(half-bridge) work. I perfectly understand how a car smps works then come does the two work?What are the differences,advantages,disadvantages,current capabilities?Why would anyone go for that instead of buying a really big transformer?(considering you might smoke the FETS,the headache of the switching circuit etc...)
Is this the same power supply used in crt monitors?I got the guts of a 17" crt monitor and it has a ferrite core transformer similar to the one's used in car smps (1 mm airgap on centre limb? what for?!).
Am just being curious,not planning to build any.
Another thing is how a power inverter works;all i know is that the 12v input is stepped up to 240/110 V DC then switched to a square wave output,how its done?...not a single clue!
Would anyone please explain these?
Monitors almost always use flyback supplies, due to the voltages required (i.e., ~100V supply for the HV section, which in turn makes the EHV for the CRT), at moderate power (~100W, except for the big ones, which might use something different*).

*Trinitrons are commonly seen with "different" power supplies. For instance, I've seen one which used self-excited oscillators, controlled with saturable reactors. Possibly LLC resonant type. Trinitrons regularly take upwards of 300W so they have their reasons.

Switching supplies are cheaper, more efficient, more stable and lighter than linear supplies. Need more reasons? No, complexity is not a reason -- you do that once, then make a million of them -- in production, NRE costs are the easiest to pay back.