2 providers offer same features
mail & Caldav/Carddav
X is recognized by emclient so everything is managed under the same entry
mail & Caldav/Carddav.
Y recognizes only the mail
and Caldav/Carddav has to be entered under a different entry.
in the EmClient UI there is no difference
but in the accounts management there are 3 entries when there should only be 2.
there is no actual problem, but if you could adress this in a later update it would be nice.