Just from the order, you can't tell. Chemisorption can have all sorts of orders, from first order (one homolytic bond cleavage, no lateral interactions) to extremely complex (multiple surface diffusion processes and reactions involved). Physisorption is more likely to have simpler mechanisms and therefore higher orders are less likely because there are no bond-breaking steps, but lateral interactions may also destroy the simplicity there.

Since physisorption and chemisorption are differentiated by the binding energy, it's better to measure that. If you use TPD for that, complex desorption kinetics may be required in order to reproduce the spectra completely, but what counts is the energy you get out of it.