Hermes and Heron are separate families of Israeli unmanned aircraft: Hermes is made by Elbit Systems and Heron by Israel Aerospace Industries. Both are used for intelligence, surveillance and reconnaissance. The Hermes 900 and full-size Heron have different endurance and payload specifications.
Hermes 900
Elbit describes Hermes 900 as a medium-altitude, long-endurance multi-role aircraft with sensor options for ground and maritime missions. Its specification lists a maximum takeoff weight of 1,180 kg, up to 350 kg payload and endurance up to 36 hours. Options include electro-optical and infrared sensors, radar and electronic-intelligence payloads. Actual fit varies by customer.
IAI Heron
IAI describes the Heron as a MALE unmanned aircraft for strategic, tactical and homeland-security missions. The company lists endurance up to 45 hours, an operating altitude above 35,000 feet and payload capacity up to 470 kg. The aircraft can carry up to six mission payloads concurrently and supports line-of-sight and satellite communications. Heron variants include Tactical Heron and Heron TP, with different configurations.
The full-size Heron has longer listed endurance and a higher listed payload than Hermes 900. Sensor suite, communications, operating rules and mission requirements determine which aircraft fits a particular task.
Elbit’s Hermes 900 product page lists its specifications and payload options. IAI’s Heron product page describes its multi-payload role. See also the companies’ wider portfolios.