Bill starts a retirement fund at age $21$ and plans on depositing equal annual amounts on each birthday, starting at age $21,$ and ending at age $60.$ He wants to have $$2$ million at age $60.$ John starts his fund on his $30$th birthday. He wants to deposit equal annual amounts on each birthday starting on his $30$th birthday and ending on his $60$th birthday. John wants to have $$2$ million at age $60.$ If the investment funds earn $10\%$ per year, calculate the amounts the Bill and John respectively will have to save each year $($rounded to the nearest dollar$)$ to meet their goals. Comment on the difference.