Home equity loan rates are typically higher than regular mortgage rates because they are considered second mortgages. That means if you default, the home equity lender is second in line to be repaid; your current mortgage would be repaid first.
If home values drop in your neighborhood, you might not have enough equity to pay off both your first and second mortgage if you have to sell your home. Or, if you fall on hard times, you might have to prioritize making payments on your first mortgage, leaving you behind on your second. Lenders consider these extra risks when offering HEL rates.