Basically, "first party benefits" are PIP benefits (including OBEL). N.Y. Insurance Law § 5102(b) defines a "first party benefits" as follows:

(b) "First party benefits" means payments to reimburse a person for basic economic loss on account of personal injury arising out of the use or operation of a motor vehicle, less:

(1) Twenty percent of lost earnings computed pursuant to paragraph two of subsection (a) of this section.
(2) Amounts recovered or recoverable on account of such injury under state or federal laws providing social security disability benefits, or workers' compensation benefits, or disability benefits under article nine of the workers' compensation law, or medicare benefits, other than lifetime reserve days and provided further that the medicare benefits utilized herein do not result in a reduction of such person's medicare benefits for a subsequent illness or injury.
(3) Amounts deductible under the applicable insurance policy.