Technically, only the first two are different as the Galaxy Note 10+ 5G is simply a 5G version of the Galaxy Note 10+. In other words, you're not getting anything other than the 5G support with the 5G version.
Of course, for many this immediately raised the question as to why there's no 5G version of the standard Galaxy Note 10? After all, it is not only smaller for those who don't want a phone with a massive 6.8-inch display, but more importantly, it is also cheaper and therefore likely to be accessible to more people.
Well, there is actually a Galaxy Note 10 5G model and it was technically announced alongside the others. The difference is Samsung did not spend too much time focusing on it because it doesn't plan to make the Galaxy Note 10 5G readily available on a global scale.
In fact, the Galaxy Note 10 5G is only set to launch in one country, Samsung's home country, South Korea.
Interestingly, in spite of it only becoming available in South Korea, Samsung did opt to showcase the standard Galaxy Note 10 5G with U.S. pricing so we have a good idea of how much it would cost, if Samsung wanted to sell it to you in the U.S.
The Galaxy Note 10 5G is priced at $1,049 making it just $100 more than the standard 4G version that is launching in the U.S. This marks a fairly notably price difference compared to the Galaxy Note 10+ 5G and its $1,299 price tag and especially considering those opting for the 5G version are paying a $200 premium on the 5G version compared to the non-5G option.
Interestingly, at $1,049 the 5G version of the Galaxy Note 10 is actually cheaper than the non-5G Galaxy Note 10+ (priced at $1,099). This may or may not be one of the reasons why Samsung has opted to not make the standard 5G phone available outside of South Korea as it looks to ensure the Plus version gets the attention Samsung wants it to.
If nothing else, the Galaxy S10e did teach us is that people are okay with getting less (even at the premium smartphone level) if they also happen to pay less as well – although the Galaxy S10e did not sell as many units as the Galaxy S10 or the Galaxy S10+ did, it still sold plenty.
While it seems logical to try to avoid one phone from cannibalizing the sales of another, and especially considering this is the first time a Galaxy Note phone has arrived in more than one size at the same time, there's likely to be other reasons involved in the decision-making process for Samsung. For one thing, Samsung probably doesn't feel much of a need to release two 5G versions of the same phone in the U.S. when the US market has yet to really establish a decent level of accessible 5G coverage.
Another reason might be Samsung still hopes you might opt for its other available 5G phone, the Galaxy S10 5G. Although that's not likely to be a better option for those in the market for a smaller phone as it is closer in size to the Galaxy Note 10+ than it is the smaller Galaxy Note 10.