Basically according to Ontario.ca website G2 roadtest refers to full license test (G roadtest which includes highway testing). So basically if you have 2 years of experience + your foreign license, you will be eligible to go for your full license test which is G road test according to drivetest.ca
I know its confusing because ontario.ca and drivetest.ca use different terms. According to ontario.ca if you pass your G1 roadtest, you get a G2 driving licence, while if you pass a G2 road test, you get a full G class license.