Difference between 诚实 and 老实 (and possibly 天真) 诚实 (HSK 4) has the meaning 'honest', just like 老实 (HSK 5), which also carries the meaning of 'honest'.

I would like to know what the difference between these two words is when they mean 'honest'.

I've found this online: 个人觉得，“诚实”形容人的品质，“老实”形容人的性格, which loosely translates to '诚实' describes a person's quality/characteristic, while '老实' describes a person's personality.

However, I don't really understand the difference; a quality you possess would indirectly be a feature of your personality right?

I've also found that '老实' carries the meaning of 'well-behaved', as well as 'naïve' (not featured in the HSK curriculum).

As a result, I would also like to know the difference between 老实 and 天真 (HSK 5) when they mean "naïve".
诚实 is honest with no further implication.

老实 is honest and possibly easy to trick.

天真 is more like innocent or even naive.