When I make coffee in the morning I put in one packet of pink sweetener, then half sugarfree liquid creamer and half milk then microwave it for 30 seconds to bring it back up to temp. And sometimes a splash of a Torani flavor for absolutely no reason. Could I just use a little more creamer instead of the sweetener? Sure. Could I use even more creamer and NO milk? Sure, I guess. I just enjoy mad scientisting my coffee. Wife just sighs and gets out of my way in the kitchen.
The first one is artificial sweetener in small sachets. Second is liquid that is also a (sugar free) sweetener but has the appearance of milk - many use it instead of milk because it acts as both. The third is a flavoring that is specifically designed for coffees, it’s what you get when you buy an eg white chocolate flavored coffee at a drive thru or Starbucks. They splash some of this flavor in.