Hi,
MCX314A-BCBT is an Ethernet adapter, and MCX314A-BCCT is Ethernet PRO adapter.
The pro cards have different benefits, for example Scales to tens-of-thousands of nodes.
You can find the benefits of each card in the product brief pages:
http://www.mellanox.com/related-docs/prod_adapter_cards/PB_ConnectX-3_Pro_Card_EN.pdf
http://www.mellanox.com/related-docs/prod_adapter_cards/PB_ConnectX3_EN_Card.pdf
Regarding the maximum speed rate and compatibility with switches- its the same for both cards.
Best Regards,
Viki