Whenever these guys show up it’s a sure miss for me. It’s ever worse cause they introduced close to each other… I’ve tried writing them down, writing some phrases but still miss them. I keep getting the meaning confused with each others.
I’m going through the same words right now! I try reading them super literally like:
年内 is literally year (年) inside (内). So, I know it’s inside the year. Which means, it’s before the year is over because it has to happen at some point inside the year not next year.
年中 is literally year (年) middle (中). So, I know it has nothing to do with the end of the year like 内. Which helps me to remember that it’s all year.
Anytime there’s kanji that are really close together I sit and talk myself through it each time like this until it starts clicking in my brain. I’m also a very visual/auditory learner so, thinking out loud helps me remember.
Do you know what kind of learner you are? Maybe I can help brainstorm a method that would work for your type of learning.
内 means inside, but it’s focus is the contrast between inside and outside.
年内 is within a year because you can’t go outside.
中 means inside, but it’s focus is on what’s happening inside. It also means duration, especially when given the じゅう reading.
年中 is what’s happening for the duration of a year, which makes it year round.
来 means come, but it’s focus is on the future, what’s happening next.
来年 therefore becomes next year
年来 is for about the years coming up, or several years.