Differential active probes are like two probes in one. Instead of measuring a test point in relation to a ground point (like single-ended active probes), differential probes measure the difference in voltage of a test point in relation to another test point
AP033 - 500 MHz Differential Probe
ZD1000 - 1 GHz, 1.0 pF Active Differential Probe, ±8 V
ZD1500 - 1.5 GHz, 1.0 pF Active Differential Probe, ±8 V
ZD200 - 200 MHz, 3.5 pF, 1 MOhm Active Differential Probe, ±20 V
ZD500 - 500 MHz, 1.0 pF Active Differential Probe, ±8 V