No, "optimized" or "upgraded" are terms they're using to mean a game from the previous generation has been given special attention to retouch it for the next gen systems. "Smart Delivery" is a unique Xbox service, and what makes it stand out is its "dual entitlement" policy.
Level 1: No Special Upgrade
First, let's take an example of a game that won't be getting "upgraded" aka "optimized" for free, or at all. Since the XSX and PS5 are backwards compatible with nearly all games of their predecessors, that could be
any game you don't see on this list. Thus, there has been no announcement these games will run a special upgraded/optimized version. It will look better on the newer consoles, even without that, due to automated resolution & framerate target improvements, but that's it. This could mean a game that ran at 900p@30fps on the Xbox One will automatically run at 1080p@60fps on the XSX. These automatic advantages are apparently far more likely to be implemented on the Xbox Series X/S than the PS5.
Level 2: Xbox One X or PS4 Pro Enhanced
Some games from the previous generation already received a special "enhanced" version for the Xbox One X or PS4 Pro with manual improvements by developers to things like textures. On Xbox, these enhanced versions are
always automatically the version used on the newer Series X/S consoles. On PS5 the carryover of enhanced titles is
more limited.
Level 3: Special Upgrade, Not Free
Next, there are games that get special attention to upgrade them for the PS5 or Xbox Series X/S. You may be charged for these upgraded versions. It's up to the developer if they wish to provide them for free, and some aren't. An example that will cost money for the special upgraded version, available on both consoles, is
Observer: System Redux.
Level 4: Special Upgrade, Free
With Sony, those that provide an optimized upgrade for free carry the "PS5 Upgrade" label. Sony doesn't demand this service be supported, and they aren't necessarily supporting it themselves. They leave it up to the developers. So, for example, Visual Concepts chose to put
NBA 2K21 on the service. Say you already own the game on the PS4. Visual Concepts is properly remastering it for the PS5, and they're going to give you this upgraded version for free. That's why it will carry the "PS5 Upgrade" label. They are also offering a free upgraded version for the newer Xboxes, and so you know, every developer who has chosen to participate in the "PS5 Upgrade" with a multiplatform game is also offering a free upgrade for the newer Xboxes. The Xbox doesn't have a special label or name for games like this, though.
Level 5: Xbox Smart Delivery (Free Special Upgrade + Dual Entitlement)
However,
NBA 2K21 is not a "Smart Delivery" title. That is only on Xbox, and it goes one step further. An example is
Sea of Thieves. Say you already own that game on the Xbox One. You will automatically get the upgraded version on the Xbox Series X/S for free. But, yet further, suppose you
don't own it on the Xbox One. You buy it on the Xbox Series X for the first time. Because it is a Smart Delivery title, you now also own it on the Xbox One, and can download it and play it on that platform. Ergo, if you buy a Smart Delivery title on either platform, you own it on both. Ownership works forwards and backwards. This is what has been dubbed the "dual entitlement" policy. That's what separates Smart Delivery titles.
Furthermore, to their credit, Microsoft has promised to put every first-party title it makes on the Smart Delivery service. That's a big deal. That shows whenever it is directly under their control they will go the extra mile.
Level 6: True Next Gen Games (no upgrade necessary)
Finally, to me, a "truly next gen game" is one that will only exist on the newer consoles, and not on the older consoles. Obviously there will be no need for free upgrades or dual entitlement backwards compatibility at all with games like that. You won't really see games like this on the Xbox since it doesn't jive with their revolutionary new console strategy. That's been part of their radical overhaul shifting to a more PC-like mentality. They seek for games to run on every Xbox moving forward. The only question is what version your Xbox will be capable of running. Conversely, Sony is still trying to carry the torch of "we believe in generations", though they've already made serious concessions on this front before the launch even happened. An example is
Godfall. The benefit for games like that is the developers aren't hamstrung going out of their way to develop a version the older consoles can run. They focus purely on the latest hardware.