They both require endless repetition and are equally difficult. I get many many questions about the secret to success, the keys to success. The thing I have found in my own experience is that the secret and the key to success is patience and a desire to constantly develop better and better skills. One has to have an insatiable curiosity about creating nuance, variations in cadence, melody and enthusiasm without ever sounding insincere. Authenticity must be the rule.
Sometimes people stay at a certain skill level approaching things the same way and wonder why they can't make more money.
It is totally possible to have a voiceover career, don't let anyone say you can't. However it is incredibly important to understand that you absolutely must keep training and keep improving all the time. Having a pretty good skill level often results in simply pretty good money, not great money.
Great success and satisfaction requires the dedication of an A list athlete not casual dabbling while wondering if things will work out. We often determine the level of success we achieve by the level of commitment we make to anything we love.