Another example, Siege Tank against S.C.A.R. Heavy Gunner. Siege Tank have 360 attack and 80 defence from troops, Heavu Gunner Attack 15 and Defence from Armored Corps 60. Siege tank will kill 360 / 60 = 6 Heavy Gunners, but since Sieeg Tanks have 80 defence from troops (which they are much better protected against Troop's attack) the result will be  80 / 15 = 5,333 times more losses for Heavy Gunners, which is 6 * 5,333 = 32 Heavy Gunners losses against 1 Siege Tank's attack. If it were Scorpions instead of Siege Tank that have       240 attack and 30 defence ag. Troops, then 240 / 60 = 4, but 30 / 15 = 2 times losses for Heavy Gunners, then       4 * 2 = 8 Heavy GUnners killed, If Thunderbolt (in russian Каратель or Punisher) 360 attack and 30 defence from troops, then 360 / 60 = 6 Heavy Gunners, but 30 / 15 = 2 * 6 = 12 Heavy Gunners. In total,  1 Scorpion will kill 8 H.G., 1 Thunderbolt will kill 12 H.G., 1 Siege Tank will kill 32 H.G.  You may ask "Isn't that a little bit too much units killed?", I say that the reality should match description of units like Scorpion, Siege Tank and Thunderbolt.  I mean, most of the time you get units from Infestations and it doesn't have Troops or Armored Corps reward for defence. I wish that you could choose what type of unit should be converted from resources into units. For example, you defended the Infestation base and you get to choose the type of unit Troops, Armored Corps, Artiller or Airforce, but the the unit is randomized.  This is useful when an Infestation has a weakness and this type of troop is much stronger than other (less troops needed to complete an Infestation) rather than waiting when the type of unit you need will appear as a reward

No, when attacking only a units attack stat matters and when defending only a units defense stats matter.  What unit types are attacking determines which defense stats are used.  For infests sometimes it's useful to send 1 unit to see what types are in the infest, then use the type it's weakest against to kill it.  Being able to choose the unit type of the reward would require them to adjust some events as it would let you score a ton of points for not much work, but could be interesting.  

Thank you for your response, the reason for why I had such thought is the official page Battle outcome – Plarium Support Center | Strategy Games  the "The outcome of the Battle is determined by the overall Defence/Offence strength of both sides participating in it. In addition to the number of Units, the strength of the army is also determined by each Unit's individual statistics"