Although these two treatment ranges are very similar, the main difference is in the colour of the pigments contained in the products. The No-Yellow uses violet pigments to tone down yellow tones, for an ash violet effect. Inebrya added blue pigment to the No-Yellow Light Blue. So the latter uses violet & blue pigments to tone down yellow-orange tones, for an icy blue effect.
For an ashier look, and keeping the grey undertone the No-Yellow will be perfect for you, because the violet pigment is a more dominant pigment. But if you want a more subtle Icy Blue Blonde the No-Yellow Light blue will be the go to product as it neutralizes unwanted tones, but will not stain the hair.
It is not a requirement that you use the shampoo and mask/conditioner together and you may opt to use them separately. But the combination of the two will have an improved result as the mask and conditioner magnify the effect of the shampoo.

You can use it every time you want to neutralise unwanted yellow or yellow-orange tones. Find the frequency that works best for your hair. If you do not have to use it every time, you can use it with a normal shampoo and conditioner.
If your hair is very porous, you may experience pigment overload that will reduce afterward through normal washing but you may have a purple or light blue undertone initially.
Some clients want to leave in the No-Yellow shampoo for longer than the advised 1 – 5 minutes to get an improved result. However, this is not advised as the combination of ingredients have been tested for optimum results within the time frame advised. However, the No-Yellow conditioner / mask may be left on for up to 10 minutes, so if you want to walk around the house with your anti-yellow on, opt for the conditioner / mask as it is softer on the hair as it contains nourishing and hydrating ingredients.

So to help you choose which range is better suited for your hair, we include a table to help you decide:
I want to maintain my natural grey hair | No-yellow Light Blue |
I want to maintain my silver / ash cosmetic colour | No-yellow |
I want my hair white, not grey | No-yellow Light Blue |
I do not want to risk having purple hair | No-yellow Light Blue |
I have lots of yellow undertones in my hair | No-yellow |
I have more orange undertones in my hair | No-yellow Light Blue |
I want a very strong pigment | No-yellow |
Both of these ranges nourishes and moisturises the hair to leave it soft and shiny for that perfect blonde you’ve always wanted. So it should really be the undertone and condition of your hair that determine which one to use.