What do these cliches mean second to nothing or none?

Both "second to nothing" and "second to none" are clichés that mean the same thing: the best, the most important, or the most impressive.

Here's a breakdown:

* Second to nothing: This implies that something is superior to everything else, leaving nothing else that comes close.

* Second to none: This emphasizes that there is no one or nothing better than what is being described.

Examples:

* "Her dedication to her work is second to nothing." (Means she is the most dedicated person.)

* "Their new product is second to none in the market." (Means it is the best product available.)

Note: While both expressions convey the same meaning, "second to none" is slightly more common and sounds a bit more formal.