Bitcoin is a chain of digital signatures whereas Segwit is something else

Segwit Properties

1. Segwit transactions are none malleable

2. Miners can update their UTXO sets without witnessing the previous owners' digital signatures.

3. The previous owners' digital signatures have significantly less value to a miner for segwit coins than for bitcoins because miners do not require them in order to claim fees

4. Although a stable Nash equilibrium exists where all miners witness the previous owners' digital signatures for bitcoins, one does NOT exist for segwit coins.

5. Segwit coins have a weaker security model than bitcoins.