Cup of cooked white rice: 205 calories.
Single cup of milo and milk: 100+ calories for milo, 100+ calories for milk.
So they're about the same in energy, however that is not the whole story. Firstly, the glycemic index[0] or how fast sugars are released - rice is good (low and sustained energy release) whereas Milo is bad (fast). Secondly, the overall eating habits encouraged... Milo is encouraging time-poor, less considered, more commercial/productised single-serving consumption and provides little additional nutrition, whereas rice typically accompanies and encourages more natural foods with a more complete nutritional profile (not just "massive energy hit plus incidental protein"). Obviously the environmental overheads with respect to packaging and transport are also far worse for Milo than rice.