Purple and Japanese sweet potatoes tend to be less sweet whereas orange sweet potato varieties are very sweet. Orange sweet potatoes also tend to have much higher water content than purple or Japanese varieties which is the main reason for baking these sweet potatoes before mashing rather than boiling. Baking also concentrates rather than dilutes the flavor. Yes, these do take a little longer to make compared to boiling, but the hands-on time is decidedly less without all that peeling and chopping.