Home equity loans and lines of credit are usually, but not always, for a shorter term than first mortgages.
In the United States until December 31, 2017, it was possible to deduct home equity loan interest on one's personal income taxes.
A HELOC is a line of revolving credit with an adjustable interest rate whereas a home equity loan is a one time lump-sum loan, often with a fixed interest rate.
Like the closed-end loan, it may be possible to borrow up to an amount equal to the value of the home, minus any liens.
The survey or conveyor and valuation costs can often be reduced, provided one finds a licensed surveyor to inspect the property considered for purchase.