What is difference between PP, OPP, and BOPP bags?

The best way to distinguish between PP, OPP and BOPP bags is by understanding their use in the real world objects.  

The Polypropylene bags or PP bags are used as non-woven bags. These are treated to make them water or moisture absorbent. Sanitary napkins, diapers, air filters, etc are some of the common PP products. The same material is also used in the manufacture of thermal clothing as they provide a temperature barrier.

The OPP bags have high tensile strength, and are transparent in colour. These can withstand high temperatures but get wrinkled if used roughly. Transparent adhesive tapes are also made using the same formulation. These are hard to tear and OPP bags are used in the packaging of leather products, clothing, etc.

The BOPP bags are crystal clear polyethylene bags. Their art of manufacture i.e. bi-axially orientation gives them a transparent appearance and this makes them suitable for branding via printing on their surfaces. BOPP bags are largely used for retail packaging. The biaxial orientation increases their strength and hence they are preferable to carry greater loads. The BOPP bags are waterproof. The products inside them can be safeguarded against moisture for a much longer span of time. And that is why these are the most desirable choice in the cloth packaging industry.

The Polypropylene derivatives i.e. the PP, OPP, and BOPP are resistant to organic solvents, acids, and alkalies. That is why these are widely used in the packaging industry where transportation and storage under changing atmospheric is unavoidable. Like cling films, they protect the product from moisture and dust. These are recyclable and their manufacture involves lesser carbon footprint. So from the environment perspective as well, the PP, OPP, and BOPP bags are sustainable choice.