Another pair

Hi, now I bring these two plants assuming they are te same species, but I have not find the name yet. I would appreciate any information. Thank you.

Possibly mam. compressa sub centralifera.

Thank you very much delandmo. I have my doubts because another plant that Chris suggested as M. compressa sub. centralifera has longer spines, but I will check some photos again in the web. Thank you.

A form of M. pringlei??

Wolter ten Hoeve.

Thank you very much Wolter ten Hoeve, but I am reading that in the M. rhodantha group (in which M. pringlei is included) some spines are yellow, which is not case of my plants. Thank you.