What's the difference between a semicolon and a comma?

The semicolon is used to seperate major sentence elements of equal grammatical rank (Hacker250). The word semi means half.

The comma is used to show a pause in the reading. The comma was invented to help readers. Without it, sentence parts can collide into one another unexpectedly, causing misreadings.(Hacker235)

The Rules

To avoid common misuses of the semicolon. Do not use a semicolon in the following situtations. -between a subordinate clause and the rest of the sentence -between an apposite and the word it refers to -to introduce a list -between independent clauses joined by and, but, or, nor, for, so, or yet (Hacker253)

To avoid common misuses of the comma. Do not use a comma in the following situations. -after a coodinating conjunction -after such as or like -before than -after although -before a parenthesis -to set off an indirect (reported) quotation -with a question maek or an exclamation point (Hacker249)

To aviod unnecessary commas -do not use a comma between compound elements that are not independent clauses -do not use a comma to seperate a verb from its subject or object -do not use a comma before the first or after the last item in a series -do not use a comma between cumulative adjectives, between an adjective and a noun, or between an adverb and an adjective -do not use a comma to set off a concluding adverb clause that is essential to the meaning of the sentence (Hacker246-248)

The Usage

Use a semicolon between items in a series containing internal punctuation. between closely related independent clauses not joined with a coordinating conjunction between independent clauses liked with a transitional expression (Hacker251,252)

Use a comma between coordinate adjectives not joined by and -before a coordinating conjunction joining independent clauses -after an introductory word group -between all items in a series

Just like semicolons commas seperate items in a series, except the comma is only keeping the words from colliding. An example of the use of commas is: Kim bought rice, corn, and grits at the store. Another example is in the date and year: Today is July 10, 2006.