老实，是一种较为口语化的表达，通常我们形容某个人的性格时，会用 老实。 而 诚恳 表示 真诚、不虚伪、没有恶意，较为书面。 但实际上也没有太大的差别。（When we talk about one person, we may describe him as brave，patient， 老实 ，etc. When someone is asking you for help，if you want me to give some suggestions whether to help him or not， I may tell you ： His attitude is 诚恳， just help him）