Difference between Semi Acoustic , Acoustic, Acoustic Electric & Electric Guitar

Acoustic Guitar

The Picture below is a Acoustic Guitar. It does not have Pick Ups which are used in Guitars 
for Attaching them with an Amplifier. The One with Pick-ups are called Acoustic Electric.

Acoustic

Acoustic Electric Guitar

Acoustic Electric Guitar sounds same as the Acoustic the Only Difference is
that there is a Pick up on the Guitar which is used for attaching it with an Amplifier or Computer etc.

Acoustic Electric

Semi Acoustc Guitar

Semi acoustic Guitar is a Hollow Slim Body Shaped Guitar which can be played like a Simple Acoustic and can also be connected to the Amp which quite same Sound as the Electric Guitar.

Semi Acoustic

Electric Guitar

its important to have an Amplifier with your Electric Guitar because it can only be played with an Amplifier not like Acosutic, Semi Acoustic, Acoustic Electric You are some sort of Bound to buy an Amp for Electric lol.

Electric Guitar