Suckling helps in better production of milk and better growth of your baby. Please try direct feed first and then expressed feed. please express when she is asleep and keep it ready and first feed her directly for a min it 10min one side each feed and then give her the expressed feed. Direct feed you will also love as the sensation is different and bonding too.

No there is no difference in the nutrition value. However holding the baby skin to skin is important for growth and development as well so make sure you hold and cuddle your baby a lot.