Russia - threadbanned users in OP

Ditto. Afghanistan and Vietnam for that matter are quite different and hold serious geographical advantages for insurgency. Even with modern technology. They also hold cultural advantages too and not so obvious ones like what people are used to. If you're born and bred in an Afghan valley with maybe one dirt road in and out where electricity is born from diesel, you are used to and can take a lot more privation from an enemy than someone living in an apartment with netflix who drives to the shops to buy beer and eggs.

Can Russia win? Of course they can and will, unless there is a huge injection of Western military kit into Ukraine. What they've recieved so far is a pittance. Twenty tanks here, five howitzers there and so on. Dribs and drabs. The Russians have the kit and the sheer numbers and have learned from their initial screwups. Their kit may be inferior, but a musket is more actual use than an M-16 without bullets, or not there at all. In this new war of artillery and attrition Ukraine can't win. Though it starkly demonstrates how utterly below par the Russian forces actually are. They should have walked this and clearly haven't. With all their on paper advantage and terrain that suits they're fighting for every road, hamlet and ditch.The credit for that goes to the Ukrainian defenders.

It also depends on what we mean by "win" of course. Russia lost the second it crossed the border and headed for Kyiv. It might have gotten away far more with "doing a Crimea" with Donbas and stopping there, but they didn't. Their economy is screwed, their future investment cut off. All they have left is oil and gas and customers are pivoting away from those. They're a rusty petrol station where the owner gets 90% of the profits and the staff are on an increasingly downward pittance. Russia has some of the largest natural resources on Earth, they should be one of the wealthiest nations on Earth, but the US state of Texas alone is wealthier.

So when the dust settles and settle it will Russia will almost certainly "keep" Donbas and the land corridor to Crimea. But that's no win for them in the medium and long term. They will have "won" a crated wasteland they can't afford to rebuild, with enough of the population still there hating them for it, no matter how much they try to Russify the place. The rest of Ukraine will be dragged, kicking and screaming if need be, into Europe and the West and will never look towards Moscow again for the foreseeable future, while any Russians with eyes to see will look at Ukraine with envy.