Construction comes first
A pile carpet and a flat-woven kilim use different textile structures. The distinction affects thickness, surface and the way the pattern is formed.
Compare appropriate qualities
Look at fibre, weave and finishing rather than colour alone. A flat woven piece should not be judged as if it were a dense knotted carpet.
Practical questions for a purchase
Ask about dimensions, care, packing and provenance. A workshop demonstration can explain technique without making buying a required part of the visit.