There is my solution based on the ideas from the previous answers:

public static JObject FindDiff(this JToken Current, JToken Model)
{
    var diff = new JObject();
    if (JToken.DeepEquals(Current, Model)) return diff;

    switch(Current.Type)
    {
        case JTokenType.Object:
            {
                var current = Current as JObject;
                var model = Model as JObject;
                var addedKeys = current.Properties().Select(c => c.Name).Except(model.Properties().Select(c => c.Name));
                var removedKeys = model.Properties().Select(c => c.Name).Except(current.Properties().Select(c => c.Name));
                var unchangedKeys = current.Properties().Where(c => JToken.DeepEquals(c.Value, Model[c.Name])).Select(c => c.Name);
                foreach (var k in addedKeys)
                {
                    diff[k] = new JObject
                    {
                        ["+"] = Current[k]
                    };
                }
                foreach (var k in removedKeys)
                {
                    diff[k] = new JObject
                    {
                        ["-"] = Model[k]
                    };
                }
                var potentiallyModifiedKeys = current.Properties().Select(c => c.Name).Except(addedKeys).Except(unchangedKeys);
                foreach (var k in potentiallyModifiedKeys)
                {
                    var foundDiff = FindDiff(current[k], model[k]);
                    if(foundDiff.HasValues) diff[k] = foundDiff;
                }
            }
            break;
        case JTokenType.Array:
            {
                var current = Current as JArray;
                var model = Model as JArray;
                var plus = new JArray(current.Except(model, new JTokenEqualityComparer()));
                var minus = new JArray(model.Except(current, new JTokenEqualityComparer()));
                if (plus.HasValues) diff["+"] = plus;
                if (minus.HasValues) diff["-"] = minus;
            }
            break;
        default:
            diff["+"] = Current;
            diff["-"] = Model;
            break;
    }

    return diff;
}

You can have a look at json diff wrapper here

It has also demo page.You can use this wrapper.