Vegeta and Piccolo. What is going on between those two?

On DBZ, there have been a few times where Vegeta and Piccolo have had their bouts. What is going on between those two? Is it a power thing or do they just not like each other? Do you think it is because the Saiyans, who were once under Freeza's power, used the Nameks therefore causing them to believe that Nameks were beneath them? I have always thought there was something racial going on there. I may be wrong. This isn't a serious question (obviously), but one I wanna know other peoples' thoughts on. Thank you.