Blub blub blub, I hope the boiler was cool when the water came up.

As the railroads spread around the world the were sometimes differences it track width but most of the rolling stock looked pretty much alike. The Locomotives, however, being so big and heavy tended to be locally made which led to a different look.

and

Of course England had dozens of different designs.

Thomas, Percy, Henry,...

Variety abounds...

Everyone gets into the act...

And we continue...

More variation...

Around the world...

Can't forget...

And last but not least...

That canal tug is a pretty specific design. I assume it's cogged to get up the lock inclines.

Also, since they're small, the cog may help it (traction-wise) tug those ginormous ships and boats.