Thunderbolt and USB-C ports look identical, and they work in pretty much the same way. The broad-brush answer is that ...
Apple’s older 12in MacBook features one 5Gbps Gen 1 USB-C port, while the later Intel MacBook Air (2018 and later) and MacBook Pro (from 2016) boast either two or four 40Gbps Thunderbolt 3 ports.