Nope, completely different protocols although some of the same connectors are used (
SFF-8643 -> SFF-8639 for a PCIe mobo -> U2 for example).
Some controllers like the
LSI 9400 series support both SAS and NVME, but not both over the same ports at the same time (IIRC you might need a proprietary cable to use it with NVME drives).
Edit: I think only the 9400 series is using 8643, regular U2 is indeed 8639 as i386 points out below but I think the connector on the motherboard is usually still an 8643.