The difference is actually Nvidia is a much more formidable competitor than Intel ever was and still.
Nvidia is on it's own. They play their own game, and completely disregard the competition. They did it when they had during the PhysX times, when their marketshare was around the same as AMD/ATi. Even if intel, suddenly managed to get around 10% of dGPU market overnight, nVidia would don't give a dang. They walk with the proud stance, making the look, they are sole GPU maker, ever were and ever will. Nothing will change. They will set their own prices, and strenghen the market dependancy on their closed proprietary ecosystem.
And that's the whole point. No GPU vendors are able to penetrate the market, if they will follow the nVidia's flute. They must disregard nVidia, as they disregard everyone else. AMD and Intel must push their own game, despite competition. They must do their best, as there's no rivals are. This includes undercutting nVidia, and follow their own budgets, and their BOM and requirements, and set the pricing accordingly. Not like now, where AMD has the tech like much cheaper to R&D and manufacture, but somehow manages to sell the products with the pricetags of nVidia's R&D budget and premium. This doesn't work. AMD is in the situation, when they must sell their cards cheaper, and sacrifice margins, in order to get the marketshare. This is just stupid. AMD just teased people with their decent cards like 6800XT/7900XT, and they just drop the advancement, in hi-end, and even fully competitive mid-end, first time for the decade, and bail out so abruptly. And the sales, availability and marketing is stagnant and uncertain to say the least. AMD has to use the situation, while people are warmed for AMD products, and make some refresh of monolithic RX6800XT/6900XT, with some architecture improvements, and maybe on smaller more efficient node, and sell it as e.g 8600XT/8700XT for about $300 and $350-400, and the sales would be huge.
Intel priced their card below the competition. Yes their current products are lacking, and are inferior at power efficiency and high performance. But if they will be able to keep the smae full steam pace, and deliver the better products on the round three, they have a chance to gain much bigger mindshare, marketshare, and momentum and turn the tables drastically, and swiftly. This might be wishful thinking, but IMHO, Intel, has more theoretical chances to overcome AMD, with same or bigger marketshare, than AMD with their sluggish marketing and management. Considering how they fix their drivers, and even do complete overhaul, after overhaul, being first time into dGPU market...
Don't get me wrong, though, AMD has really nice products. But they have neither capacity, nor advantage, speed, and most importantly the wish to shake the market. Their products are either missing, not available for purchase, or their price is awful. AMD have not control over the partners, which can screw up them up, the damage contro and quality contro are non-existant. It just looks, like they don't even care about consumer GPU division at all.
And that's why Intel has more chance. Even without dirty tricks and bribes, and own foundries, Intel has stronger corporate stucture, are more known and widespread and OEMs will gladly jump their ship, abandoning AMD, as soon, as Intel will make a breakthrough.
Even if AMD will keep medium-range-only GPU products, they have to deliver in time, have the agressive pricing and be on par, or even have slight advantage. But tha'ts hard, and maybe that's why they don't even try anymore with Radeon division. After all, the APU OEM sales with AI give them certain high marging flow of money.