Hi, for example on the space of symetric matrices, the positiveness >= 0 (all the eigenvalues of the matrix are positive) is an order relation on this space.
For arbitrary square matrices M, N we write M ≥ N if M - N ≥ 0; i.e., M - N is positive semi-definite. This defines a partial ordering on the set of all square matrices. One can similarly define a strict partial ordering M > N.
The wikipedia page here https://en.wikipedia.org/wiki/Positive-definite_matrix is should answer your questions.