The short answer is that the digital aspect of the two is similar, if not the same: digital games are sold once and can be used anywhere the user can log in to the account. That seems to be the same both before and after Xbox's 180.
The biggest difference is in the analog aspect of Xbox One. Steam doesn't have a physical sales component - it was created specifically to avoid that scenario. Xbox does though, but because it forces analog sales into a digital construct (via forced installs of games - not a bad thing necessarily, just a design decision they made) it forces the analog component to function by the same rules as the digital sales component.
Going all digital was always a choice with clear positives and negatives. You could avoid the negatives (one being no resale, for example) by sticking with physical discs for certain games. It was always a decision. However with that design decision to force the analog into the digital construct, Xbox one wanted to remove that choice.
With Xbox One's prior rules, physical copies of games could only be sold once. That's it. Then it would require an additional secondary sale to Microsoft to function. And the primary sale could only happen to select retailers. That's breaking what's understood and expected from that optional analog construct due to design decisions, without providing any additional value to the consumer.
Yes, forced installs allows mimicry of the all-digital experience and adds a certain amount of convenience, but doesn't allow any advantages beyond the all-digital experience. Certainly not enough to make up for the lack of choice in forcing consumers into a suboptimal construct.
The key here was subverting customer expectations and taking what used to be a choice and trying to A) force it into what MS preferred, and then B) trying to monetize that. It reeked of a money grab because it added no new value beyond what was already available via digital sales while removing established value for consumers.
tl;dr: It's different than Steam because Steam is one all-digital service while Xbox One tried to force all physical and digital sales into following the same ruleset as an all-digital marketplace.
I fear that I sound like the language police, but really, your comment was already fairly complex before I had to puzzle over what you meant by "analog" and "all-digital" as if this device had a coaxial output to a CRT TV.