vac pulled v's fibreglass noob question

can any one enlighten me on the differences between these two construction methods and the final result pros and cons of the two

Depending on the item you are making, a fibreglass object has the best potential for maintaining defined, sharp lines in an object whereas a Vac-form is much easier, lighter and cheaper.

Fibreglass is also usually less flexible than vac-forming (depending on the type of plastic used).

For something like the chest armour, both methods are fine and it all comes down to what you want to pay and what is available to you at the time.

thanks mate