Ruslan commented "I thought it was similar with 'sooner or later'".
In modern English, "later" and "latter" are simply two different words, with different pronunciations. You can stop right there. I'm about to mention another meaning of "latter," which is worth knowing in case you see it used that way--but don't try to use it.
I am always curious about word derivation and history, Although these words have separated, there is an UNCOMMON meaning of the word "latter:" it CAN mean more recent, later in time! Each of these three sentences is correct and means the same thing. Only the first is ordinary everyday English, the other two are a little bit "literary" and old-fashioned.
"Recently, we have been seeing wild turkeys in our neighborhood."
"Of late, we have been seeing wild turkeys in our neighborhood."
"Latterly, we have been seeing wild turkeys in our neighborhood."
In real life, the only time I ever hear "latter" with that meaning is in the correct full name of the Mormon church: the "Church of Jesus Christ of Latter-Day Saints," "LDS church" for short (which is what Mormons themselves say). That use of the word "latter" was natural in the 1830s when the Mormons were founded. It's unnatural today.
It seems obvious that the words "later" and "latter" must have a common derivation, and you sent me to the dictionary to check, and they are both derived "from the Old English læt slow, late."
Anyway, they are different words now, with different sets of meanings.
There is a lot of that in English. Our perverse spelling preserve strange bits of history and word origin. A lot of them reflect the way words were pronounced centuries ago--the pronunciation changes but the spelling stays the same.