Not the same, no. Evaporated milk is done with a vacuum meaning it boils away at refrigerated temperatures, not high temperatures. Boiling milk with heat makes the protiens clump and curdle. Yes, it will thicken, but it won't behave the same in cooking or baking.
Many low fat cookbooks use commercially prepared skim milk evaporated milk in place of cream but you still can't cook it with much heat without curdling the protiens unless you also bind it with starches or other binders. And the taste is different as is the texture and mouthfeel. Not bad necessarily, but certainly different.
The trick with the powder is to get it into suspension in high concentrations. Milk is a colloid like whipped cream, meringue and so on. This is one of the reasons it evaporates well as it is dispersed in a water-based fluid.