At 10mbps half duplex, the protocol is nearly the same. Just twisted pair uses differential pair signalling and and coax uses a shared ground and high or low on the center conductor relative to the shield (IIRC). And twisted pair relies on a hub to create a bus. From there you go to 10M/full duplex where the rx and tx pairs are fully separated so collision detection can be disabled.
100base-tx increased the symbol rate, added speed and duplex negotiation (layered into the existing link pulse signaling), but otherwise kept things the same; you can even run a 100base-tx hub.
1000Base-T is a wide departure at the signalling level; all 4 pairs are used simultaneously, bidirectionally, the symbol rate is the same as 100base-tx, but each symbol carries more bits. But the ethernet frames are pretty much the same. (Larger frames started appearing around the same time as gigE, as I recall, but that might not be accurate)
100base-tx increased the symbol rate, added speed and duplex negotiation (layered into the existing link pulse signaling), but otherwise kept things the same; you can even run a 100base-tx hub.
1000Base-T is a wide departure at the signalling level; all 4 pairs are used simultaneously, bidirectionally, the symbol rate is the same as 100base-tx, but each symbol carries more bits. But the ethernet frames are pretty much the same. (Larger frames started appearing around the same time as gigE, as I recall, but that might not be accurate)