Is there a concise way to express "without further specification" or "based on what is known", as in
Without further specification, items A and B are indistinguishable.
and
Based on what is known, options A and B are equally good choices.
An idiom in this ballpark would be "on the face of it", but I am intending something more precise.
"Ostensibly" comes fairly close, and this might be appropriate for the first example above (if A and B are to be distinguished based on visual appearance), but this has connotations of being specious and doesn't fit with the second example.
I realise that the Latin phrase a priori may be appropriate in some contexts, as in
A and B are, a priori, equivalent.
but this has a quite precise meaning which does not fit all cases (independence from all experience, rather than limited experience as in the first example above).
Edit: I had hoped to keep things general, as have found the above construction ("without further specification...") to come up quite often in my work, but it has been suggested in the comments that it may help to provide an example of what "A" and "B" could be. Suppose you have two apples, both of which weigh 100g. If you are only told their weight, but no other information, you have no way of distinguishing between them. However if you are also told the colour of the apples, and one is green whilst the other is red, you can.