Is it true that parents favour one child over another? Does this mean that their parents love them less?

It doesn't mean the parent loves them less but it may seem that way to the children who aren't favourites. I was always my dad's favourite and it always showed. It was also his way to punish the boys through spanking but not the girls. Combined, this made my brother resent me for a long time until we were mature enough to work out our differences.