Because the loans need to be attractive on the wholesale market, conventional loans have higher minimum credit scores.
These loans usually have a lower interest rate.
They often require 3% as a minimum down payment (instead of the 20% which is needed to eliminate the mortgage insurance)
Their appraisals have easier qualifications than those of FHA.
The mortgage insurance premium is less.
Many lenders offer Lender Paid Mortgage Insurance at a slightly higher interest rate so that the buyer can eliminate that extra monthly payment which is included in the total monthly payment.
While many think that a 20% down payment is required for all conventional loans, many lenders now offer low down payment options.
FHA
Generally will accept lower scores than Conventional.
Allow more of a seller assist,(towards the closing costs) 6% instead of 3%.
Requires a down payment 3.5% instead of 3%.
Property has tougher than conventional loan appraisal qualifications.
Mortgage Insurance (charged by the lenders for not having 20% down payment) is a higher monthly premium.