Elevation data is notoriously misleading. A typical example is bridges where the road is nearly flat yet ground surface changes dramatically. Another problem (less and less of an issue) is where elevation was computed from inaccurate readings taken from a cliff or ravine next to the road. Differences across platforms can also be due to different road selection. Google Maps tends to route on secondary roads, other applications may prefer tertiary roads or tracks.
I use
bRouter. They provide estimated travel times that are a close match to my touring experience (actually, I use Locus PRO/Android, where travel times can be tweaked a bit more).