I'd like to add that Rank usually refers to their official rank, for example, Sasuke Uchiha is legally a genin. However, power-wise, he's right at the top. So under classification you would put his status as a S-Rank Missing Ninja. 

Anjin Uzumaki, for example, never went through the normal village system, so he has no rank. Under rank, it says "None," and under Classification it gives his status as a seal master. While seal mastery is not direct canon, I believe it is no large stretch to believe that some people would attain a high enough level of skill in the area to be dubbed as such.

The Ranks, I believe, are Academy Student, Genin, Chunin, Tokubetsu Jonin, Jonin, ANBU, and Kage. Correct me if I'm wrong please. Sannin is not a rank, nor a classification; it is a team. It literally means "three people."

There is another type of jonin, I think Jonin Commander or something like that. From what I know from my time being with the series, Sannin is a title given to the three strongest shinobi of a village, the same as Kage so it would be a classification. The team was not called The Sannin, it was named something else because they were dubbed that by Hanzo of the Salamander of the Rain Village and the rest of the world accepted the rank rather quickly and easily.

A good example is Team 7, the team made up of Sakura, Sasuke and Naruto who were dubbed the Three Way Deadlock which is a title of sorts though whether or not that is a classification is hard to know.

It's not a title that can be earned by the "three strongest", but you've already answered that yourself. The other rank is Head Ninja.

It's only not attainable because Hanzo is dead and hes the only one who can dubb anyone to be a sannin. Anyways, thanks Kay.

Hanzo dubbed Orochimaru, Jiraiya, and Tsunade the "Legendary Sannin." There are no other holders of that title.

The Three Way Deadlock is not a team name, that was a chapter title...

You misunderstand like always, I never said that the Three Way Deadlock is a team name, you assumed that and it is nore more than a chapter title dude, it is also a title which shinobi have given the three current strongest shinobi, Team 7.