Seated calf raises = soleus being the protagonist of the movement.
Standing calf raises = the calf (gastrocnemius) being the protagonist of the movement. The gastroc is not really active when the knee is bent.
Do you know of any correlation between seated/standing and high/long calves?
The gastroc is the muscle that's higher up on your calves, and that is more directly trained doing standing calf raises.
The soleus is the longer one that lies underneath. So if you have a huge soleus and small gastroc, you can give the illusion that you have "higher calves" if you neglect the soleus and blow up your gastroc (not sure if this is very possible though).
Even then, your gastroc might be too low anyway.