What causes more damage: A Bulldozer or a Freight Train?
The destructive power will depend on the Momentum which is the product of mass and velocity. Momentum should not be confused with Kinetic Energy which is half of the product of the mass and the square of the velocity. A freight train would normally have both a greater mass and velocity than a bulldozer.
The damage that any moving object can cause is down to its kinetic energy - a product of its mass and speed. A large bulldozer might have a mass of 30-40 tons, and at full speed is probably only capable of 15-20mph. A loaded freight train is typically 3000 tons of more, and moving at 30-40 mph. You figure out which is going to do the most damage!
Pretty easy to outrun a bulldozer as it is on tracks and very cumbersome. Trains? Not so much, but they too are running on tracks and easy to side step, if armed with a full complement of grey matter cells. You don't say which sport, but if football, I'd go with a dozer there.
I would rather a train come after me as all I would need to do step off the tracks - but at full speed a train has much more weight and thus energy required to come to a complete stop. But either one will conjure up an image of destruction and unrelenting power. I would go with bulldozer - better visual imo.
Both of them will kill you. You will be equally dead. The difference is this: A bulldozer will flatten you into something with a different shape than your original body, but the parts will probably remain connected together. A train may tear you into 2 or 3 pieces, but the total size of the pieces will be relatively unchanged.