Local Offset and Input Movements impacted by framerate

Hi,
I have 2 Pawn ships that go forward, with a Floating Pawn Movement.
Ship1 uses a Add Input Movement, with a Max Speed of 500
Ship2 uses a Add Local Offset of 300*WorldDeltaTime
For both, I repeat these steps in a Timer loop.

Both ships move at the same speed onscreen, with these settings and no framerate limit.

When I limit the frame rate, here is what I got:
fps 15
Ship1 same speed
Ship2 a lot quicker

fps 30
Ship1 same speed
Ship2 quicker

fps 60
Ship1 same speed
Ship2 slower

fps 90
Ship1 slower
Ship2 a lot slower

What could explain those differences ?
Even the Add Input Movement has a different behaviour with a fps90 limit ?