Here's a difference:
true && false == false
true || false == true

&& and || are logic operators. Research "Boolean logic" or "Boolean
Algebra". && is pronounced "AND", || is pronounced "OR".

& and | are bitwise operators. They perform bitwise "AND" and "OR"
operators.
SEE: http://www.leepoint.net/notes-java/data/expressions/bitops.html
Or search for "Java Bitwise Operators" (the link above is the first
google result I got)

The "||" and "&&" operators are "short-circuit" operators. If
they know the result after evaluating the first sub-expressions,
they never even look at the second (that is, if the first expression
is false for "&&" or true for "||").

This allows you to write things like:

 boolean isValid = (bar != null) && bar.isValid();

If the "bar" variable holds null, the "bar.isValid()" is never
evaluated.
If instead you write:

 boolean isValid = (bar != null) & bar.isValid();

and "bar" is null, then this gives a NullPointerException.

/L

see http://mindprod.com/jgloss/oroperator.html
http://mindprod.com/jgloss/andoperator.html
http://mindprod.com/jgloss/mccarthyoroperator.html
http://mindprod.com/jgloss/mccarthyandoperator.html

evaluate their right-hand argument.

false && foo()   -- foo() is never called because the value of the
expression is determinable without calling foo() -- it is false since the
left hand argument is false.

true || foo()  -- foo() is never called because the value of the expression
is determinable without calling foo() -- it is true since the left hand
argument is true.

In contrast,

false & foo()  -- foo() is called.

true | foo() -- foo() is called.

-- Adam Maass