在两个json中比较数据，并在python中保持差异。

import json

def compare_json(json1, json2):
    diff = {}
    for key in json1:
        if key not in json2:
            diff[key] = json1[key]
        elif json1[key] != json2[key]:
            if isinstance(json1[key], dict) and isinstance(json2[key], dict):
                nested_diff = compare_json(json1[key], json2[key])
                if nested_diff:
                    diff[key] = nested_diff
            elif isinstance(json1[key], list) and isinstance(json2[key], list):
                if json1[key] != json2[key]:
                    diff[key] = json1[key]
            else:
                diff[key] = json1[key]
    
    for key in json2:
        if key not in json1:
            diff[key] = json2[key]
    
    return diff

json_str1 = '{"name": "John", "age": 30, "city": "New York"}'
json_str2 = '{"name": "John", "age": 35, "city": "Boston"}'

json1 = json.loads(json_str1)
json2 = json.loads(json_str2)

difference = compare_json(json1, json2)
print(json.dumps(difference, indent=4))