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

I am a mother of two now for about a year. But honestly, i feel embrassed about saying this that i am favouring more on one kid instead (my second son) I guess its the amount of bonding you had with the child. I was there fr my second born since birth and been fully breastfeeding him, where the bonds are created. For my elder son, i only started looking after him full time when he was 6 months old. Yes i still dote both of them as my kids. But somehow others will see them i favour more on the younger child rather then the elder child