The Definitive Edition on PC is actually not based on version 1.4.
While Update 1.4 was specific to the original 2012 release, its fixes were foundational for the Sleeping Dogs: Definitive Edition sleeping dogs update 1.4
While 1.4 addressed immediate bugs, subsequent updates (up to 2.1) continued to polish the experience. Significant later changes included: The Definitive Edition on PC is actually not