The travel time is calculated for each segment by using speed-limits for different waytypes [see Travel Time Calculation] (https://github.com/GIScience/openrouteservice-docs).
The reason why both queries output a different driving time is that the ORS determines different speed-limits to the ways.
According to GitHub, OpenRouteService was forked from GraphHopper 0.10 which in turn had been released in March, 2018. Both their source code and their driving profile parameters are different. Likewise, their map data is most likely not from the same date. Do you think that can affect the result too?