The external physical differences. Making differentiating differentials easy. The tag is still your best bet on getting accurate info on your rear end.
After we’d seen the new Mars rover prototype and had what Mara described as the best apple juice in the whole world, we left Kennedy Space Center to do something we’d never thought we’d ever do in a million years, the REAL reason this day was the best day ever: FALCON 9 ZUMA ROCKET LAUNCH!!!!!(x1000) *flailing Kermit arms*