One framework for two desktop platforms
Using CrossVcl you focus only on your VCL application and CrossVcl makes it cross-platform.
Win API bridge
CrossVcl provides low-level Windows API bridge to macOS.
CrossVcl provides native macOS equivalents for almost all standard controls like TEdit, TMemo, TComboBox etc.
TCanvas and TBitmap behave on macOS like on Windows.
Many custom controls work on macOS like on Windows unchanged.
CrossVcl works with all Embarcadero Delphi since XE3 to Berlin.