The key differences between construction loans and a home mortgage lie in the amounts involved, the interest rates charged, and repayment periods. There is only so much that a banker is willing to advance you in the form of a construction loan while mortgages carry extensive loan limits. Additionally, construction loans carry high and variable interest rates while most mortgages are fixed rate. Construction loans must also be paid within a short period – usually 12 months – while mortgages repayments can extend to as much as 30 years.