Both read as green at a glance. The difference is whether a second, warmer colour is genuinely present in the same iris: green-hazel carries visible gold or light brown alongside the green, usually concentrated centrally, while a plain green iris is comparatively uniform.
How much warm flecking a green iris may carry before it becomes green-hazel is entirely conventional, and green-hazel is not a category any study records.
Green-hazel is routinely photographed as either plain green or plain hazel depending on white balance, so images are a particularly poor basis for choosing between these two.
No photograph or online colour-picker tool can definitively classify which of these categories a specific pair of eyes belongs to — classification is inherently somewhat subjective, and lighting/camera effects change the apparent result.