Many times when I open up laptops, there are several different types of screws (not talking about screws of different lengths here)
I was wondering if there was a rule of thumb that is followed for the color/material coding of the screws. It would save me a lot time remembering what screws go where.
The blue threading is probably some sort of thread locking compound. Thread locker prevents the screw from vibrating loose - sort of like a glue. There is no color coding for screws - just whatever matches the case area where they are used. The head size is determined by how much pressure you are putting on the screw and how much area you are trying to spread it over. If you have higher pressure, you will probably want a bigger head so you don't crack the plastic - it spreads the load across more of the plastic.
First and formost, the easiest way is to keep it organised to start with- there's a reason I have pill boxes for working on computers.
The blue 'thread' is a standard screw that has had something similar to locktite added to it, and the ones without arn't.
Most removable screws i've seen are small, and need an eyeglass screwdriver to open. I've seen larger screws used in areas that arn't visible usually, and hidden behind 'stickers', especially around the bezel.
HDD screws are flat headed, short and relatively fat compared to standard laptop screws.
