There are a few differences between the two, but first - a brief intro to matcha:
All ‘real’ matcha green tea powders have the following traits:
(Note - A lot of cheap ‘green tea powders’ are sold as matcha. These powders are often dull green, lack aroma and taste very bitter. While all matcha is a form of green tea powder, not all green tea powders are a true ‘matcha’. Real matcha should have all these steps, shading, hand picking, stone grinding)
If you plan to be making matcha smoothies, green tea lattes or desserts with matcha - then the Cooking Grade is better suited. It’s more economical and has a stronger flavour that pairs well with sugars, fats and other flavors. It’s what I personally use for all my smoothie and matcha drink recipes.
If you plan to drink matcha as a tea just with water, then the Kenko Premium Grade would suit you better. It has a slightly sweeter, delicate flavour profile, very slight astringency and whisks to produce a lovely crema, similar to an espresso coffee. It’s also visibly bright greener - like an intense jade green.
(Kenko Premium Matcha Green Tea Color)
Many people are surprised just how green high grade matcha is - it has to be seen first hand. This grade of matcha is typically reserved for Japanese tea ceremony, and is often referred to as ‘Ceremonial Grade Matcha’. It’s best when prepared with a traditional bamboo whisk (chasen) and scoop (chasaku).
(Whisking matcha with a bamboo Chasen)
All Kenko Matcha is produced in the Nishio Region in southern Japan, and come from the same tea farms. The leaves are harvested once a year in the spring, and stored as dried tencha leaves before being stone ground only to order. Any matcha you purchase from Kenko Tea has only been processed into matcha powder within the last month. This ensures freshness, vibrance and the intense green colour and ‘green tea’ aroma that a quality matcha should have.
The main difference between Kenko Cooking Grade and Kenko Premium Grade is in the leaf selection, and blending.
All matchas are ‘blends’, that is leaves are harvested, graded and sorted according to their individual colour, aroma and flavour profiles. One batch of matcha may have leaves from a few different farms within a region. So unlike a single origin coffee where each batch can be traced to a particular farm - matcha powdered green tea is always a blend.
The youngest, greenest leaves found at the top of the tea plants are reserved for the higher grades of matcha. While the leaves at the base of the plants are reserved especially for the cooking grades. This isn’t to say cooking grade is lower in quality, the same care is taken in every aspect of production. From the shading of the tea leaves, the harvesting by hand to the drying of the tea leaves and blending.
(grinding matcha tea on stone mills)
Cooking grade is blended especially for, you guessed it cooking. With a bolder flavour, slightly more astringency and stronger ‘green tea’ flavour that combines with other ingredients.
(Kenko cooking Grade Matcha Tea)
The difference in price between the two grades is mainly due to the stricter requirements for premium grades of matcha. As only the youngest, most delicate leaves are used, the supply is more limited and this affects the price. Also one thing to keep in mind is 90% of matcha produced in Japan is consumed within Japan, so what’s left for export is in high demand and short supply - further increasing the cost.
Well if you are keen to try matcha the traditional Japanese way, I'd recommend purchasing a Matcha Tea Set, to experience a properly prepared matcha tea.
On the other hand if green tea smoothies and green tea latte's are more your style - then start with the cooking grade.
Although you can always try both ;)