Both .bct and .bcp files come from a software called Business Card Designer Plus. Everything points to the fact that bct to bcp conversion pretty much describes the using of templates (.bct) for making new designs that can be then saved as new projects (.bcp).
But since both extensions are not only used for many other formats, but also are used as common abbreviation, it might very well be possible that some other kind of conversion is doable as well and not just in file conversion sense.
Updated: October 30, 2023