Comparisons

The basic Boolean expressions compare between two expressions:

<expr1> _EQ_ <expr2> Equal

<expr1> == <expr2> Equal

<expr1> _NE_ <expr2> Not Equal

<expr1> != <expr2> Not Equal

<expr1> _LT_ <expr2> Less Than

<expr1> < <expr2> Less Than

<expr1> _LE_ <expr2> Less than or Equal

<expr1> <= <expr2> Less than or Equal

<expr1> _GT_ <expr2> Greater Than

<expr1> > <expr2> Greater Than

<expr1> _GE_ <expr2> Greater than or Equal

<expr1> >= <expr2> Greater than or Equal

Notes:

It is possible to compare expressions of different types (that is, one numeric expression and one string expression). However, this is not recommended, and may lead to unexpected results.
In the old GPP, only the _XX_ comparison operators were supported. In GPP2, new "standard" operators were added (after the operators used in the C Programming Language). Both forms are supported, and can be used freely.
See the following sections on exactly how expressions are compared:
Comparing Numeric Expressions
Comparing String Expressions
Comparing Mixed Expressions - Not Recommended.