The word mortgage has to be explained clearly before we start. Any property that is pledged to the financial institution/ bank until the repayment of a loan is done is called a mortgage. Generally houses, land etc are taken as mortgage.
The word mortgage loan would mean two different things in Indian scenario and US scenario.
In US, in case of a loan for new house and a loan for renovation or extension of existing house, both would be called a mortgage loan. This is because, the house that is going to be constructed or the house which is going to be extended or renewed, both are treated as mortgage basically.
In India, a loan sanctioned to construct a new house would be called a home loan even though it is going to be taken as mortgage for the loan. The loans for renovation and extension of an existing house would be called a mortgage loan or a home refinancing loan in the Indian scenario.
The loan amount or quantum of loan is generally slightly lesser than the actual current value of the property kept as mortgage. This is to ensure that the financial institution/ bank can recover the loan amount even if the loan is default.