Just to add to Adams description and detail, the name is an indicator of your intention for access to the funds.
If you intend to take it all, or a big chunk at a given date in the future, you may choose withdrawal, as you intend to withdraw the funds, and so we progress to a defensive position to stabilise the funds ready for withdrawal.
If you intend to access the funds in chunks over time or draw an income, then you may chose income. In this case we look to stabilise a proportion of the funds ready for you to draw as income while allowing the rest to continue to seek growth ready to be accessed at a later date