What is the difference between a regular towel and a tenugui towel?

They are both made of the same material which is cotton.
A tenugui does not have the same absorbency as a towel, but it dries faster and doesn't clutter.

Why are the sides not sewn together (the "unfinished" look)?
Tenugui started as a cloth being cut from a long piece accordingly to the person's needs.
The person can have it as short or as long as they wanted.
This is the reason why the sides look like they were just cut (and the "unfinished" look stuck around).
Plus it's less-bulky and dries quickly when wet.

For those who want to use it as a handkerchief, folding into thirds will yield a good size.

The repetitive patterns work well in that it can be cut anywhere and design consistency will be retained.  

■Made in Japan
■Dimensions : 13.5” x 35.5”
■Materials: Cotton