A perfect analogy is the German invasion of Russia in WWII (with a bit of abstraction). The German force had advantages in the technological engineering of their war machines and weapons, better training, and years of recent combat experience. The Russians had numbers, really, and that was about it. Numbers to fill factories and crank out guns, tanks, and planes; numbers to fill those tanks, planes, and the ranks of their infantry that individually were rarely the equal of anything the Germans had.
For a more specific example, the Russians produced more T-34 tanks than any other AFV in WWII, cranking out around sixty-four thousand of them from 1941 to 1945. At the height of production, they were rolling out around 1300 T-34s a month. Known design flaws and crew inconveniences were ignored because changing the production to accommodate such things would only cost more money and take more time. The only allowed changes were things that would make them faster and/or cheaper to produce. Systems were engineered to contain as few parts as possible and were streamlined later to reduce the number of parts even further. A new turret was introduced at a later point that was considerably more comfortable for the crew, but that was secondary concern - it was done because it was almost entirely cast in giant sand molds instead of the whole thing needing to be welded together which was both faster and cheaper.
Know what the German tank with the highest production numbers was? The StuG III, somewhere around ten-thousand. By all accounts, the StuG III was one of, if not the most successful tanks in the war given how many enemy vehicles were destroyed vs their own casualties, but in the end, the slower production times and smaller production numbers could not win out against a horde of inferior enemy forces.