A 30-amp RV service provides a single 120V/30A circuit (3,600 watts), while 50-amp service provides two separate 120V/50A legs (up to 12,000 watts total) — the difference mainly affects how many high-draw appliances (AC units, microwave) can run simultaneously, not phone or laptop charging.
Practical note
Off-grid and RV charging systems are more forgiving of imperfect setups than people expect — the main failure mode is undersizing the battery bank or solar input relative to actual daily use, not choosing the wrong charger.