They're not the same. 如果你有空吗 would be the same as asking "if you have time?" with a question mark. 吗 is the particle that changes a statement into a question. In this case however, you wouldn't use it. 如果 is normally used in a conditional sentence. So here's an example of how you would use it: 如果有空，我明天去图书馆 (I'll go to the library tomorrow if I have free time.) If you want to ask the question you can add the question particle: 你有空吗?　or add the positive+negative verb: 你有没有空　(do you have free time?) You can use the positive +negative structure of asking questions in this situation. i.e. : I don't know whether you have time or not : 我不知道你有没有空?(literally: I dont know you have don't have time?) As for 如果你到时间, I haven't heard of this phrase. It literally means: "If the time is when you arrive" which doesn't make much sense.

Hi, i answer your question. 如果你有空吗？(That is not so good, you can say with chinese：如果你有空 or 你有空吗？) 1、如果你有空(if you are free)：this sentence is declarative sentence. 2、你有空吗？(are you free?) ：this sentence is question sentence. 如果你到时间( if it's time to do something for somebody) so that is not the same

if here doesn't mean 如果，if here means 是否

你有空嗎? = 你有時間嗎?

什么意思，不懂