System.out.println will print on a new line where System.out.print will print and the same line.
Println() won't print on a new line, it will terminate the current line with a newline character or sequence. In other words, println() will print an end-of-line character, while print() will not. If you invoke println() after a print(), the argument to println() will append to the argument to print(). Here's an example:
Running this snippet in a program produces Jeff Bosch on one line, then places the cursor at the beginning of the next line.
Give a man a fish, he'll eat for one day. Teach a man to fish, he'll drink all your beer.
Cheers, Jeff (SCJP 1.4, SCJD in progress, if you can call that progress...)