When you want to move funds from your Openledger account to another account (wallet) which exist in bitshares blockchain you need to use 'Send' function. 

All account which were made via different web-interfaces ( for example via wallet.bitshares.org ,gdex.io, etc) exist in bitshares blockchain. How all this platforms connected you can read here.

When you want to move your funds to another exchange or to your external wallet (which exist in external blockchain) you need to use "Withdraw" function. Instructions how you should make withdrawal you can find here