For the differences, looking at the technical report [1] on selected benchmarks, rounded score in %:
Dataset | Gemini Ultra | Gemini Pro | GPT-4
MMLU | 90 | 79 | 87
BIG-Bench-Hard | 84 | 75 | 83
HellaSwag | 88 | 85 | 95
Natural2Code | 75 | 70 | 74
WMT23 | 74 | 72 | 74
[1] https://storage.googleapis.com/deepmind-media/gemini/gemini_...