I have made some research and found that these two verbs are of similar meaning. Cambridge Dictionary gives this definition of include:
to contain something as a part of something else, or to make something part of something else:
The bill includes tax and service.
Tax and service are included in the bill.
[ + -ing verb ] Your responsibilities will include making appointments on my behalf.
verb [ T not continuous ]
If an activity, situation, etc. involves something, that thing is a part of the activity, etc.; and also
If a situation involves someone or something, he, she, or it is affected by it:
Research involving the use of biological warfare agents will be used for defensive purposes.
[ + -ing verb ] The operation involves putting a small tube into your heart.
The second accident involved two cars and a lorry.
What's more, one of the definitions of involve in CALD is:
to include someone in something, or to make them take part in or feel part of it:
So... involve = include?
The first solution I thought of is to define include as "inanimate-inanimate/inanimate-animate" sort of situarion (let us from now on abbreviate inanimate-inanimate as I-I and so on: I-A and A-A). and to define involve as I-A only:
Package (I) includes rice (I) / I-I
Daphne was included on the guest list / A-I
Solomon was involved in the crime / A-I
However... this system just falls apart, and not only because there is an A-I intersection, but because of this
Also because of this (COCA: research involves vs research includes = 102 vs 73)
And because of the same result which BNC gives (frequency of research involves vs includes = 34 vs 14)
My question is: what is the difference, if there is any? Can we say that include is used when we are talking about non-continuous events (shopping list, research as a paper document, etc... in fact, these are not even "events") and, thus, involve is used when we are talking continuous events, finished or unfinished (research as a series of actions, some historical process, crimes, etc)?
This took a little while, so thanks in advance for reading and taking your time to write an answer!
P.S. I've read this thread, but I am nevertheless concerned about the problem as the thread users offered some controversial answers.