(a) The term mortgage loan shall mean any loan made on the security of residential, nonresidential, improved or unimproved real estate where the lender relies upon such real estate as security for the loan, including a loan secured by a lien on an existing ownership interest in certificates of stock or other evidence of an ownership interest in, and for a proprietary lease from, a corporation or partnership formed for the purpose of the cooperative ownership of real estate. The term mortgage loan shall not include any loan not considered to be a loan upon the security of real estate within the meaning of section 103(4)(b) of the Banking Law.

(b) The term lender shall mean a bank, trust company, savings bank or savings and loan association organized under the provisions of the Banking Law.