[opensuse-security] cryptsetup syntax

Apropos cryptsetup, I have a question regarding the command syntax. On the web, sometimes I see cryptsetup --cipher aes-xts-plain64 and sometimes I see cryptsetup --cipher aes-xts-plain64:sha256. Is adding :sha256 an equivalent to adding -h sha256 or is this somethin different? Is adding -h sha256 sufficient to chose the hash algo? What is the purpose off adding :sha256 at the end of the cipher algo? Once I even tried cryptsetup --cipher aes-xts-plain64:blubber -h sha256 and adding :blubber did not give an error message, it worked, this makes me wonder, if adding :foo does make any sense at all... Thanx