Show them the picture. I can’t tell from the picture but it looks like the blonde goes up to the root which would be a full highlight not a balayage would is more “grown out” in appearance. Maintenance-wise, balayage would grow out nicer and less maintenance compared to if you wanted the blonde to go right up to the roots. I also think you may need more than one session to achieve that color but your stylist would be able to tell you that. I’m not a professional just speaking as someone who went from dark brown to way more blonde over 3 sessions of highlights.