Colons and Semi colons

First we will show what a colon and a semi colon is. A colon looks like ":" and a semi colon looks like ";". So now that we are clear on what's being discussed let us discuss what they are and their differences.

A colon can be used between two independent clauses to emphasize the second clause.
The guitarist knew what to think of his band: they were absolutely terrible.
Here we are emphasizing what a person is thinking, which is the second independent clause in this sentence.
A colon can also be used after an independent clause in relation to an idea following the independent clause such as a quote or list.
The most powerful world leaders: America, China and Russia.
In his address late last night the President said: "Today is a great day for America. Our economy has recovered just in time for re elections."
The greatest invention ever conceived: sliced bread.
A colon is used at the end of business greetings
Dear Supervisor:
Used to separate hours and minutes when telling time
1:57 pm
Finally to separate verse and chapter in the bible
Acts 18:9
And those are the uses of a colon.

The semi colon can be used to join two independent clauses when the second clause restates the first or they are both of equal emphasis.
I am tired; I am very sleepy.
A semi colon can be used to join two independent clauses when they are separated by a conjunctive adverb or a transition.
Conjunctive adverbs are: however, therefore, moreover, furthermore, thus, meanwhile, nonetheless and otherwise.
Transitions are the phrases: even so, in fact, for example, that is, for instance, in addition, in other words and on the other hand.
On one hand he is a good person; on the other hand I need my goat.
Finally to join elements of a series that already includes commas such as listing the capitols of nations.
Washington D.C., America; Moscow, Russia.

And so where the differences stand: A colon is used for lists, quotes or when you wish to emphasis the second independent clause over the first independent clause as well as being used in formal letters, the telling of time and quoting the bible.

A semi colon is used when two independent are of equal emphasis or the second clause is greater in emphasis, used to separate two independent clauses when there is a transition or conjunctive adverb separating them and finally to join elements of a series that already has commas in it.