No. Locking the keyboard does just that. locks the keyboard, keeps the phone running.
standby is like putting you tv into standby, it reduces the amount of power it is using.
so yes although standby will effectively keylock, standby SAVES BATTERY.
i.e. go to bed, have 90% battery, put in standby. wake up 8 hours later and STILL have 90%.
"That's it then. Cancel the kitchen scraps for lepers and orphans, no more merciful beheadings... and call off Christmas."