Greetings! I hope I don't come off as too blunt when saying this, but this question is egregiously and utterly wrong. Neither Napoleon nor Hitler began their invasion of Russia before Winter, in fact, quite the opposite: they both began their campaigns in Russia in the summer. Both the French Emperor and German Fuhrer wished for the campaign to be swiftly over before winter came, because both of them already knew (in Napoleon's case from the study of Charles XII of Sweden's invasion in 1708-09, and in Hitler's case from Napoleon's own failure in 1812). In fact, Hitler agreed with his generals that the war against the Soviet Union was meant to be mostly concluded before winter, that is, the majority of key strategic objectives (Moscow, Leningrad, Stalingrad, and the Caucasus oilfields) were to have been captured before temperatures plummeted and the army would suffer from even greater attrition.

Note: I must also advise that you take whatever is posted on r/HistoryMemes with a serious grain of "mematic liberty" if you will. Historians are all now agreed that neither Napoleon nor Hitler planned to invade Russia during the Winter, but rather that their campaigns were not planned to last until then.

The Wehrmacht was therefore not wholly ready for when the Winter of 1941 came. Logistics problems hampered the delivery of winter supplies and clothing (which had only been ordered for 60 divisions, as that was how many the Wehrmacht envisioned would be needed to remain in Russia once the campaign was mostly over). Neither Hitler nor Napoleon wished for their campaigns to last until the winter months, but that was what ended up happening in the end. Whilst I cannot weigh in on what failures led to Napoleon's Grande Armee having to suffer at the hands of "General Winter", I can give some insight from a previous thread I weighed in on about the Third Reich's situation:

If the Red Army could be destroyed in a single campaign and the Soviet resources brought under German control, the Third Reich could face the eventual Anglo-American alliance with greater confidence and attritional resistance. However, this all rested on the key assumption: if the Soviets could be taken out in one campaign.

To that end, Hitler approved the plans for Operation Barbarossa (red beard, after a highly respected Emperor of the Holy Roman Empire) on December 13th, 1940. Preparations were to be completed by May 15th, 1941 and the main plan envisioned three powerful thrusts. More on that in a moment, because we must first take into account the sheer scale of this venture.

In the Low Countries, the Wehrmacht had deployed some 91 divisions over a front of about 965 kilometers (600 miles), against the might of the Red Army, they deployed 146 divisions, along a front of 2092 kilometers (about 1,300 miles) in length. The Red Army divisions facing them in June 1941 totaled some 150 divisions, though most were understrength and the whole Soviet armed forces was still suffering from something the original question has brought up: Stalin’s Purges. The Red Army’s top brass had been absolutely decimated between 1938-39. In the Red Army alone, the purges had eliminated: 3 out of 5 marshals (among them the renowned Mikhail Tukhachevsky), 50 out of 57 corps commanders, and 154 out of 186 divisional commanders. A new batch of officers and generals was being trained, but these men would take time to grasp the intricacies of mechanized warfare.

The Soviet equipment, on the other hand, was also a mixed bag. Though they had 20,000 tanks at the onset of the invasion, more than three-quarters were unserviceable. 1,500 KV-1s and T-34s (both of which were shockingly superior to any German panzers of the time and impenetrable to all but the heaviest field guns) had been deployed, but these formations lacked radios and were inexperienced. The Soviet Air Forces had about 8,000 planes, but most were old designs and crewed by pilots who had yet to face the battle-hardened Luftwaffe. Soviet artillery on the other hand, was a formidable enemy if encountered, though in June 1941 they were still suffering from the purges as well.

Barbarossa was formed of a three-pronged thrust into the Soviet heartlands, striking at key cities such as Leningrad, Moscow, and Kiev, as well as seizing the Caucasus oilfields in the south. The first target was entrusted to generalfeldmarschall Wilhelm Ritter von Leeb’s Heeresgruppe Nord (Army Group North), formed of six mobile and twenty-three infantry divisions. Kiev was entrusted to generalfeldmarschall Gerd von Rundstedt’s Heeresgruppe Sud (Army Group Center), formed of eight mobile and thirty-three infantry divisions (among them some Romanian divisions). The prize of the Soviet capital however, fell to generalfeldmarschall Fedor von Bock’s Heeresgruppe Mitte (Army Group Centre), formed of fifteen mobile divisions and thirty five infantry divisions. Among the troops under Bock’s command were the 2nd and 3rd Panzergruppen of Erich von Manstein and Hermann Hoth, two of the most battle-hardened and well-equipped contingents in the entire force. The general tactics were similar to those which had worked so well in the West: mass encirclements of Soviet forces enabling swift strikes towards key points. However, the critical factor here, was supply. The encirclements were planned to take place as close as possible to the Western border as possible, enabling the resupply and reinforcement of the various army groups to sustain the campaign. It was this critical factor which soon shot the bolt of the entire Russian campaign.

On June 22nd, after a crucial month’s delay at Hitler’s insistence to deal with Yugoslavia and Greece, the operation was launched. In the first few weeks, all three Army Groups made spectacular progress. By July 13th, some 4 million Red Army troops had been killed, wounded, or captured. The Wehrmacht had pushed the borders of the Third Reich as much as 800 kilometers (600 miles) further. Massive encirclements of hundreds of thousands of troops had taken place around Bialystok, Minsk, Kiev, Kharkov, and Vyazma (not including the countless smaller encirclements of sub-division formations). Chief of staff general Franz Halder remarked in his diary on July 3rd:

“It is thus [in light of the success of the invasion] probably no overstatement to say that the Russian Campaign has been won in the space of two weeks. [However], the sheer geographical vastness of the country and the stubbornness of the resistance, which is carried on with all means, will claim our efforts for many more weeks to come.”

As if fulfilling Halder’s insightful assessment, two forces then interfered, both with devastating consequences.

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