What is difference between diverticulitis and diverticulosis?

it seems that we have a problem in figuring out what disease my brother has gotten because of his heavy use of alcohol. We were told that he had one of the above diseases, but we can't remember

The suffix -osis means 'abnormal condition', whereas the suffix -itis mean 'inflammation'.

Diverticulitis is brought on - an inflammation occurs. Diverticulosis can be a condition from birth or from a long time ago, and can be an ongoing condition.

Well they are spelled different

diverticulitis-inflammation of one or more diverticula, characterized by abdominal pain, fever, and changes in bowel movements.

diverticulosis-the presence of saclike herniations of the mucosal layer of the colon through the muscular wall, common among older persons and usually producing no symptoms except occasional rectal bleeding.

Many people have small pouches in their colons that bulge outward through weak spots, like an inner tube that pokes through weak places in a tire. Each pouch is called a diverticulum. Pouches (plural) are called diverticula. The condition of having diverticula is called diverticulosis. About 10 percent of Americans over the age of 40 have diverticulosis. The condition becomes more common as people age. About half of all people over the age of 60 have diverticulosis.

When the pouches become infected or inflamed, the condition is called diverticulitis. This happens in 10 to 25 percent of people with diverticulosis. Diverticulosis and diverticulitis are also called diverticular disease.

Read all about it in the link below.

I think you may be off the mark on these,and need to look for a different name for his problem, as nether seems to be from drinking.
Diverticulitis, are little pockets formed in the colon, where food and undigested particles can collect,
Diverticulitis, is the result, and very painful, when these food particles lay there and rot, or infect. If not taken care of it can result in colon surgery to remove the infected area, making the sometimes temporary use of the colostomy bag necessary.

Diverticulitis is the inflammation of the diverticulum, which is an outpuching sac in the intestines and Diverticulosis is the condition or the disease there of.