This is something that comes up in specs a lot, here's a quick explanation...
The ring finger of the left hand goes on the G key of the flute. Because this finger is shorter than the middle finger it is more comfortable, and ergonomic, for this key to be offset (brought closer), means it's easier to reach, than if the key was inline (keys all in a straight line).
For some time now the offset G has been a standard feature on closed-hole student flutes, making it an easier reach for young students with small hands. Once a student advanced to an open-hole flute, many would then change to inline G, with silicone or cork plugs used to close any holes still difficult for the player to reach.
Does it make a difference?
Well in terms of advantages, an inline G key can be integrated right into the mechanism of the other tone hole keys. This makes manufacturing a little easier, as an offset G key needs its own set of ribs, posts, and key rods, which adds a bit of weight to the flute.
However, with modern considerations to efficient design and comfort, we think it's important that all our instruments are designed from the hands first. This consideration is our way of helping to prevent performance-related hand and forearm injuries, such as tendonitis and carpal tunnel syndrome. Ultimately we want to keep people comfortable so that they can focus on being the best they can be!
All John Packer flutes have off-set G's, and our kinder flute the JP010CH is designed for the very smallest of hands who can't even reach a curved head flute!