Doesn't have to be just oil any type of MJ...same principal difference depends on the method of ingestion
Smoking is easiest but wastes the most THC, CBD up to 70%
Making an oil you may extract 60-100% of the actual THC, CBD or nothing at all...Then pending on the method of ingestion you will only take in a certain %
So quality, method of extraction, and type of ingestion all come into play when it comes on making an educated choice on what the best product for price is