Bees can only directly metabolize sugar solutions up to 50% in strength (1kg sugar to 1 lliter of water)
, anything above 50% needs diluting with water back down to 50% before they can "feed" on it. This can mean they need to find water and take extra flights and use extra energy.
It's all about whether you want them to directly utilize the feed or whether they need to do extra work to be able to use it, or store it.
2 parts sugar to 1 part water is more commonly used when you want them to store it in combs for winter. It's closer to the 80% (or so) they are aiming at for stores; so is easier to evaporate off the small amount of water necessary for them to produce sugar honey.
But use what you wish, they will take either.
As they say you can take a horse to water....etc.
