Definitions: 

And: Connects or joins two or more phrases, words, sentences, etc. Or: It connects two or more possibilities, options, or alternatives.

When to Use And?

• It connects or joins two or more phrases, words, sentences, etc. • It can also be used to introduce an additional clause. • When using and, it is imperative to keep in mind that it can only be used to connect one additional clause or word at a time.

Examples of Using And

I eat only bread and butter for breakfast. • She had to choose between biology and chemistry ─ and it was very hard ─ she loved both the subjects. • We conducted an experiment on radioactive compounds and isotopes.

When to Use Or?

It connects two or more possibilities, options, or alternatives.

Examples

She had to choose either singing or dancing; not both.He had to rush, or else he would have missed the train.