Little has been publicly reported about the Phoenix Ghost and the official said in a press briefing he "loathed" to reveal more about its capabilities.
The Switchblade, however, is a tactical drone mostly for locating and destroying troop positions, but it can also harass tanks and armoured vehicles as the munitions can be outfitted with a heavier anti-armour warhead that is launched quickly and in numbers.
The drones are unique in their ability to hover above a potential target, strategically waiting for the right moment to conduct a precise strike, known as "loitering munition".
The Phoenix, developed by the US Armed Forces and California-based AEVEX Aerospace, can reportedly fly up to 100mph (160km/h) and carry a significant payload.
"This was rapidly developed by the Air Force in response specifically to Ukrainian requirements," John Kirby, a Pentagon spokesman, said.
Ukrainian soldiers will be travelling from Kyiv to Poland in the next few days and weeks to receive instruction on the US' new drone systems.
The new tranche of $800m in military assistance is expected to include 72 155mm howitzers, 144,000 artillery rounds, the Phoenix Ghost tactical drones, as well as field equipment and spare parts.
President Joe Biden's decision to quadruple the amount pledged in an arms package announced just last week reflects what is shaping up as a major ground battle in Donbas.
Biden said the new package was tailored to help Ukraine's forces address the growing Russian offensive in the country's east, which he said would be a different kind of fight than that in the north around Kyiv, where Ukrainian forces successfully beat the Russian invasion back in the first six weeks of the war.
"To modernise [former US president] Teddy Roosevelt's famous advice, 'Sometimes we will speak softly and carry a large javelin'. Because we're sending a lot of those in as well," the president said.
"We're in a critical window now of time where they're going to set the stage for the next phase of this war," he added. "And the United States and our allies and partners are moving as fast as possible to continue to provide Ukraine ... the weapons their forces need to defend their nation."
