||02-26-2013 06:12 PM
They're fundamentally the same in that they both have a primary winding, a secondary winding, and magnetic framing called the core on which the windings are placed. They differ in physical size of the various components including wire thickness, and number of turns of wire around the core, and this is optimized for the current the transformer is supposed to carry and the supply voltage and the desired output voltage(s).
Some years ago I was talking to an electric company line man about transformers. I forgot exactly what he asked me but I started explaining about primary and secondary. He interrupted me and said that there are no coils inside the (distribution) transformer, it's just filled with oil. Since he worked with the things and I didn't, I did not bother to argue with him even though he was dead wrong. I suspect that all he knew is that you feed in 7000 volts or so and get out 120/240 volts. Now I had worked with small transformers like furnace transformers and I know that they have coils.