You can build an expression tree which contains an inequality comparison using Expression.NotEqual method. For example, you have the following code.
bool value = 31 != 32;
Console.WriteLine(value);
Here is the code that is required to build the same functionality using expression tree.
Expression greaterThanExpr = Expression.NotEqual(
Expression.Constant(31),
Expression.Constant(32)
);
Console.WriteLine(Expression.Lambda<Func<bool>>(greaterThanExpr).Compile()());