The following ar features of the NEC-1 code that differ from AMP2:
• A new current expansion is used with continuous current and current derivative along wires. The expansion enforces a new condition at multiple-wire junctions and allows for current flowing onto the end cap at an open wire end
• Where a wire connects to a surface, the surface-current expansion is related to the current at the base of the wire rather than at the center of the last wire segment.
• An optional voltage source based on a discontinuity in current slope is available.
• In the thin-wire approximation, the current filament is on the wire axis and the observation points are on the surface.
• An optional extended thin-wire approximation is available.
• Either a perfectly or imperfectly conducting ground may be used with surface patches.
• Either a perfect or imperfect ground may be used in incident plane wave.
• Some constants have been changed including the velocity of light (2.998*10⁸m/sec.) and the default frequency (299.8 MHz)
• The wire-segment connection numbers have new meanings.
• The radiated field is the field at a range R multiplied by R with R approaching infinity. In AMP and AMP2, the field is multiplied by R/lamda).
• Both near electric and magnetic fields may be computed. The NF card is no longer used.
• Charge density may be printed for wires.
• The PT card is no longer cancelled by a new EX card.

The following are features of NEC-2 that differ from NEC-1:
• The NGF option has been added.
• The restart option has been removed.
• The Sommerfeld/Norton method has been added.
• Maximum coupling between antennas may be computed.
• wires may have tapered radius and segment lengths
• Patches may be specified as triangles, rectangles, or quadrangles.
• Rectangular surfaces with multiple patches may be specified.
• The SS card for surfaces has been eliminated.

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