Designed as an interceptor and air superiority fighter, the highly maneuverable Su-27 has a top speed of about 1,800 mph and a maximum ceiling of about 59,000 feet.
The F-15, by comparison, has an edge on the Su-27 with its maximum speed of 1,875 mph and maximum ceiling of 65,000 feet.
Source: globalsecurity.org, US Air Force
The Flanker can be armed with up to 10 air-to-air missiles, including AA-10s and AA-11s. It can also be armed with FAB-100 bombs and one 30 mm GSh-301 cannon.
The F-15, however, can only be armed with eight air-to-air missiles, including four AIM-9 Sidewinders and four AIM-120 Advanced Medium-Range Air-to-Air Missiles or eight AIM-120 AMRAAMs. It's also armed with an M-61A1 20mm, six-barrel cannon.
Source: globalsecurity.org, US Air Force
The Su-27 that crashed on Tuesday was a Su-27UB, which is a trainer variant.
The Su-27UB, which first flew in 1985, can be fitted with the same munitions and weapon control systems as the Su-27. But it has a few slight modifications, namely that it's a two-seater instead of a one-seater.
Source: globalsecurity.org
"This is a sad day for the United States and Ukraine," Maj. Gen. Clay Garrison, Commander of the California Air National Guard and the director of the Clear Sky exercises, said in a statement.
"Our deepest condolences go out to the family, friends and fellow Airmen of both the U.S. Airman and Ukrainian aviator who were killed in the incident," Garrison said.
The crash is still under investigation, and the US pilot's name is being temporarily withheld pending notification of next of kin.