Physical Differences:Cat5e: The thinnest cable out of the 3 types, easy to handle as it can bend easier around corners and more of it can fit in a single piece of trunking.
Cat6: It’s a bit thicker than Cat5e as it contains more copper and has an inner divider that divides the 4 pairs, depending on the make the sleeve will also be harder and less prone to “Kink”
Cat6A: Thicker than Ca6 and contains more copper and the pairs are twisted tighter than Cat6
Color: Mostly used is Gray and blue but they come in almost any color such as Green, Yellow, Black, Orange, Red etc.
Shielded: Shielded cable can come in any type (Cat5e, Cat6 or Cat6A). The cable will have a shield inside the sleeve protecting the cable against electrical and other interference.
Outdoor Cable: Outdoor cable is usually black, they cost more than indoor cable and will always be shielded and UV protected.
Speeds VS Reliability VS Budged::For the fastest speed and reliability choose Cat6A and you can get 10Gig speeds if the distance of the cable run is 50m and less.
If you need speed and reliability and you only need speeds of 1Gig then Cat6 will work for you. Cat6 is cheaper than Cat6A. If the run is less than 50m you can get speeds up to 1Gig per second.
Choose Cat5e if you have a limited budged and you are fine with speeds of 100 mbps to 1gig depending on the cable run.
At this stage most companies opt for Cat6 as this will prepare them for future speeds as the requirements grow.