There is a difference between cleaning, sanitizing and sterilizing. First off let’s get sterilizing out of the way because as home brewers, sterilizing is not something that can be done economically.
To make something sterile you have to remove all traces of bacteria and spores, no chemicals available to home brewers can do that. Sterilization can only really be done in an autoclave or with heat for an extended period.
What us home brewers need to do is remove as much of the bacteria as possible to levels where they won’t be able to infect our beer. When we talk about sanitising we are actually talking about disinfecting.
Cleaning on the other hand is something everyone is familiar with and usually involves scrubbing and elbow grease. The purpose of cleaning is to remove all the organic material and dust from your equipment.
So now we have our terms defined, cleaning gets your equipment to the point where you can’t see any dirt then sanitizing reduces invisible bacteria to negligible levels, meaning they won’t be around in enough numbers to infect your home brew.