BIG OR LARGE?

 Large is used for describing an item that comes in various sizes and have been previouisly clasified into size categories. For example, If you went into McDonalds and said, 'Man, look at the size of that drink! It sure is large." you would be wrong if it was actually a small or medium or extra-large drink.

 Don't use Large to describe your oppinion.

Small and Big – are these opposites? We are taught that they are. But I  think Little is the opposite of Big. First you're a Little kid, then you're a Big kid – but you may still be small. Big can mean stature, but it can also mean age. Big brother as opposed to Little brother.

Small and Large – I think these are the correct opposite pairing. Although it's not so much "opposites" really as it is a comparison. A size small is not really opposite of size large. It's just smaller. Large and small should be used for sizes or amounts. A large sum of money, a small shoe.

WHAT IS THE DIFFERENCE BETWEEN BEGIN AND START?

They are  synonyms and mean the same thing.

Synonyms: begin, commence, start, initiate, inaugurate

These verbs denote coming into being or taking the first step, as in a procedure.
 Begin, commence, and start are equivalent in meaning, though commence is more formal, and start often stresses the point where inaction turns to action:
The play begins at eight o'clock. The festivities commenced with the national anthem. We will stay on the platform until the train starts.
Initiate applies to causing the first steps in a process: I initiated a lawsuit against the driver who hit my car.
Inaugurate often connotes a formal beginning: “The exhibition inaugurated a new era of cultural relations”