What do "3G," S," "C," "Plus," "S Plus," "SE," "X," "R," "S Max," and "Pro" have in common?
They're all suffixes Apple has added to identify its iPhones.
For 10 years, Apple (AAPL) had a two-year upgrade cycle: In the first year, Apple completely redesigned the iPhone. In the second year, the iPhone got some internal upgrades but remained the same on the outside.
That was true for the 3G / 3GS, 4 / 4S, 5 / 5S, 6 / 6S and X / XS.
But in other years, Apple bucked the trend. The iPhone 7 and iPhone 8 had the same design as the iPhone 6 and iPhone 6S, and there was no 7S or 8S. (There was no iPhone 9 at all).
The bigger versions of the iPhone were once "Plus," and then they changed to "Max."
The colorful, plastic one was the iPhone 5C. The low-cost iPhone was the SE.
The slimmed down, basic version of the iPhone last year was labeled "R," and this year it's just "11." The souped up version is "Pro" this year (it was "S" last year).
Got all that?