Anyways, don't get into the habit of using quotation marks either way. Most people including myself use apostrophes because they work indefinitely.
Quotation marks ("") are strings that can be used everywhere. Apostrophes ('') are used for networking.
messageAll('',"text");
The '' part is a networking string. In this case, it's the type of message to send. When it's a blank networking string it just messages them in the chat. Otherwise it sends a different message type with the text being the content for the message type to use when it reaches the client.
For example:
messageAll('',"hello my name is bob"); //messages the entire server in the chat with "hello my name is bob"
messageAll('MsgItemPickup','',0,hammerItem.getID());//tells the entire server that the hammer should be in their first tool slot