the three replies above are NOT correct. when 好容易 and 好不容易 are the adv, they are the same. for example, 我 好容易 才到了日本 = 我 好不容易 才到了日本

好容易 means very easy but 好不容易 means very difficult

There is no difference in meaning between them. But 好容易 is far less common than 好不容易. This is the very reason why some people who have answered your question don't know, or perhaps just can't think of, this usage of 好容易.

Like everyone explained above, 好不容易 means "not easy". The reason that you brought up the question is that, I guess, you've heard somebody used “好容易” to express the meaning of "not easy". I can only say that the person misused it or his pronunciation was really vague and made you miss the word "不". You know, sometimes, some people cannot articulate, and it sounds like he swallows some words. 好容易 means "very easy", it is grammatically correct but, formally, people in mainland China don't speak in that way, people in certain regions might do, such as Taiwan, Hong Kong, Guangdong and Fujian. Example: 这个问题很容易的！——people in mainland China 这个问题好容易的！——people in certain regions. Although some people in mainland China, especially young girls would speak it in this way for fun or being cute.

好容易 means it's very easy, without any difficulty 好不容易 means put a lot of efforts to reach the goal or to do something