In A replaced B the focus is on the role or place previously occupied by B: we are told that it is now occupied by A, and we are not told anything about B, other than that it doesn't occupy that role/place any more. The word replace doesn't tell us whether B was destroyed when A came to occupy that role/place, or it now continues to exist somewhere else.
A displaced B, on the other hand, does imply that that B was not destroyed by the replacement, that it shifted to some other role/place (possibly more limited than the original one).
Thus 'the blueprint process was displaced by the whiteprint process' implies that there continued to be some use for the blueprint process somewhere, after it was replaced by the whiteprint process in most of its uses. If one does not want to imply that, one should say that the blueprint process was replaced by the whiteprint process.
The criterion for whether it is OK to say that A displaced B is, however, not very sharp. Depending on what A and B are, it may be that B lingers for some time in some smaller role before it disappears completely. Or it may be that B continues to exist in some very, very narrow domain. People may disagree on when such limited-time or limited-domain existence of B is sufficient to warrant saying that it has been displaced by A.