Jillian is correct. The graphs show different motion.
The first graph shows the position of an object over time. The position is increasing at a steady rate ... the object is moving at a steady speed. The speed is the slope of the position line. That's 25meters in 4seconds ... 6.25 m/s .
The second graph shows the speed of an object (not velocity) over time. The speed is increasing at a steady rate ... the object is moving with a constant acceleration. The [magnitude of] acceleration is the slope of the speed graph. That's 25meters per second in 4seconds ... 6.25 m/s² .
If you drew a distance/time graph for the object that's accelerating like in this second graph, the blue line would be steadily curving upward, not straight.
