The Differences between Linear and Cyclic
As far as chemical makeup goes, these two forms of glucose are exactly the same. The only real difference between the two is the shape and presence of each kind. This first difference is the shape, which can be cyclic and linear. Cyclic are by far the more common form of glucose by far, especially when it comes to water solutions. The problem with finding a finite ratio for how much of each form will be present at a set time is because they are always changing forms.
Uses
Glucose is used in cells, specifically in the mitochondria, during the process of cell respiration. And since most of the glucose in a water solution is cyclic, the large majority of glucose used in respiration is cyclic. Glucose is one of the three basic sugars, along wiht fructose and galactose, and is necessary to fuel living organisms. It is possible for linear glucose to be used up in this way, but it is very uncommon due to the incredibly small quantities in water solutions.