In terms of whether the mix is right for the bees or not, yeah it does not matter that much when mixing fairly light. Ultimately the bees will fix it to what they want it to be.
The density of granulated sugar is roughly 1.6 times more than water. If you mix by volume: mixing equal volumes of sugar and water together is going to be a 1.6 to 1 syrup, not a 1 to 1 syrup. Mix any way you wish and what works for you and your bees. However, being in a technical profession, being clear on the method of measurement and the units when stating a number does matter, a-lot, .. at least to me it does. When we tell each other 2:1 or 1:1 or 1.5:1 syrup , it does make a huge difference in the thickness of the syrup produced whether that spec is by mass or by volume.