My sporty child hasn’t been still since they were born. 😆
Very early crawling, walking etc Advanced balance, climbing, ball skills early on in comparison to twin. Needs quite a substantial amounts of exercise every day (a bit like a dog needing walked
)
Arty child always really enjoyed messy play, anything tactile, finger painting, play-dough, potato printing etc. Had a much earlier grasp of colours and shapes in comparison to twin.
Loved looking at pictures and visiting galleries from a very young age (think 18 months). I had one who wanted to stand in front of a painting for ages while the other one just wanted to run round the gallery! 
Arty child was drawing pictures with houses/people/animals etc while twin was still scribbling.
One advantage of twins is that you can observe two children, with access to the same activities and toys ands with the same parenting and see how completely different they are from very early on.
They are both bright, engaging children but their personalities and talents are quite different. They get on very well though which is lovely.