Not quite two eras, I would call it three, just to include the transition century and a half between steam engines and containers. Actually
four several eras: Human powered, wind powered, cross oceanic navigation, mechanical power, containers.
The first boats required rowers, then the shift to deeper draft wind power. But it wasn't until accurate "portable" clocks were invented that extended periods of time, two plus weeks, out of sight of land was feasible. During the mid 1800s ships shifted from wind to steam power. The early 1900s saw the shift to bulk tankers, but cargo was still breakbulk. (Barrels or boxes, stuff that could be tied together or put in a cargo net/on a pallet and hoisted out of the hold with a crane.) I want to say 1957 was the year the first container ship sailed, but it was about then. I am not sure when bulk carriers as they are now became common, but I would say either in the early 1900s with the bulk tankers or right after WWII.
So it's more than two, but there aren't so many as to make it overwhelming. Most of the eras are over a thousand years long.
I'm pretty sure I ditched the notes, but port development went through five phases from pulling up on the beach to building elaborate quays. Don't forget that the Romans did stuff with cement that we still can't do.