The two layers which differentiate thick skin from thin skin are

Thick skin covers the palms and soles. The epidermis of the thick skin, which is 400 to 600 mm thick, is characterized by the presence of all five layers. Thin skin covers most of the remainder of the body. The epidermis of thin skin, which ranges from 75 to 150 mm in thickness, has a thin stratum corneum and lacks a definite stratum lucidum and stratum granulosumReference: Krishna Garg Histology; 5th edition; Page no: 118