The human cells do not produce the same type of protein for the body to use. The difference in the proteins is a byproduct of gene expression. Our body contains cells that have different function and each of these cells have a genetic information. When the cells use their unique genetic material, that triggers the process for genetic expression. The particular genes express themselves which allows the production of a specific protein to be produced. Therefore, gene expression and protein synthesis are often considered to be a synonymous process.
Reference:
Harwood, J., & Wilkin, D. (2012, November 30). Protein Synthesis (Read) | Biology. CK-12. Retrieved September 14, 2022, from https://www.ck12.org/biology/protein-synthesis/lesson/Protein-Synthesis-and-Gene-Expression-MS-LS/