Your VP (Voting Power) allows you to vote others and increase your & their rewards. Leaving your VP at 100% wastes rewards for both you and other users. Maintaining your VP at a min of 80% daily is recommended. VP replenishes at a rate of 20% per day.
Your RC (Resource Credits) are what enables you to take actions on the Steem blockchain. Actions include posting, voting,... amongst others. RCs replenish at a rate of 20% per day.