Fastest lap is about completing the full lap quicker than anyone else in that session or race. Top speed is about the highest measured speed at a point or zone.
Why fastest lap matters
A lap time blends braking, corner speed, acceleration, traction, tire life, and driver execution. It is usually a stronger all-around performance signal than a single speed number.
Why top speed matters
Top speed still matters because it shows straight-line efficiency, engine output, gearing, drag, slipstream, and track layout. At high-speed circuits, it can shape overtaking and race strategy.
Best practice
Show both when you can. Fans get a faster read when lap and speed notes sit beside the winner, team, and event.