There is a significant difference in these two devices.
The uAvionix SkyEcho2 cannot be used in ADSB out mode with your transponder switched on. If squawking for ATC to see your aircraft you must set the SkyEcho to ADSB in only. Thus if your transponder is mode A/C other ADSB receivers wont see you. Pilotaware gets round this will some clever architecture and you can operate it with your transponder at the same time.