Which characteristic could distinguish a crystalline solid from an amorphous solid?

Crystalline solids 
1. The internal arrangement of particles is well defined. The molecules are lined up in a very particular order. 
2. They possess sharp melting points. 
3. NaCl and NaF are examples of Crystalline solids. 

Amorphous solids 
1-The internal arrangement of particles is not well defined. Molecules are not in a particular arrangement. There is no regularity in their form.
2. They do not possess sharp melting points. 
3. Glass, rubber and plastics are examples of Amorphous solids..

Yes, endothermic means it turns cold. and some chemical changes include change of tempature.