ISO 2768 is more rigid and documented. ASME leaves more to the machinist's judgment. If your drawing says "Tolerances: ISO 2768-m", it is legally binding worldwide.
The standard is divided into two parts to cover different aspects of manufacturing precision: Iso 2768 General Tolerances Pdf
Values in millimeters (mm)
Multiply mm values by 0.03937. For example, ±0.2mm becomes approximately ±0.0079 inches. Most shops using inches will round to the nearest 0.001" (±0.008"). ISO 2768 is more rigid and documented
Sources: ISO 2768-1:1989(E), ISO 2768-2:1989(E), ISO Handbook: Technical Drawings (2019). "General Tolerances: ISO 2768-m" )
The core philosophy is simple: By invoking ISO 2768 in the drawing’s title block (e.g., "General Tolerances: ISO 2768-m" ), you eliminate hundreds of redundant tolerance callouts.