Which cables for migration...
I need to migrate a 2015 MacAir to a new 2018 MacBook Pro 15" TB. What cable(s) do I need?
The MBA has Thunderbolt and the 2018 MBP has Thunderbolt 3 (USB C) so you'd need an TB<->TB3 adapter or a TB-TB3 cable. This is a similar situation many of us faced when Apple replaced FireWire with TB. At that time I concluded that the most economical way to migrate was to do a TimeMachine backup on the old and then use it to migrate to the new. I'd do the same today.