The propositions you're describing fit under the broad category of modal logic. According to the Stanford Encyclopaedia of Philosophy,
A modal is an expression (like ‘necessarily’ or ‘possibly’) that is used to qualify the truth of a judgement. Modal logic is, strictly speaking, the study of the deductive behavior of the expressions ‘it is necessary that’ and ‘it is possible that’.
When we talk of certainty, what we really mean is that that thing is necessary. So all we have to do is introduce a new logical operator:
'it is necessary that A'≔L(A) for any formula A
'it is sufficient that A'≔M(A) for any formula A
Then your proposition(s) become:
This should be read literally as:
'Everything that sufficiently has the property Sx must necessarily have the property Nx, but not everything that sufficiently has the property Nx must necessarily have the property Sx'
Sx and Nx are just predicates, and since both propositions have the same form, you can just change what the predicates mean in each case.