Is payback and the gun by Paul Langan same thing?

The Payback and The Gun are not the same thing. The Payback is a 1995 American crime thriller film directed by Brian Helgeland and starring Mel Gibson, Gregg Henry, Maria Bello, David Paymer, Lucy Liu, Bill Duke, and James Coburn. It is based on the 1969 novel The Hunter by Donald E. Westlake.

The Gun is a 2011 American neo-noir action thriller film directed by Jessy Terrero and starring Armie Hammer, Ryan Philippe, and Curtis "50 Cent" Jackson. It is based on the 1974 Japanese novel by Yuichi Nomura.