Well,both of the sentences' meaning are same and the grammars are right.In fact, 的话and 如果 can use tother too.For example,如果你需要帮忙的话，可以告诉我,it's ok. there is not big difference between them,just use them boldly,either of them or both of them is ok.

same... like "if" and "whether"

They are basically the same. But"的话"is more colloquial. And you can even use them together in a casual conversation like"如果你需要帮忙的话，可以联系我。"

.....的话，（如果）.....的话 are softer and neutral in tone and are casual and informal in style 如果is used in both colloquial and written context (more used in writing though) while .....的话is almost never used in formal or solemn texts

the complete sentence is 如果你需要帮忙的话，可以告诉我。 you can remove 如果, likes 你需要帮忙的话，可以告诉我，it is also correct. you can also remove 的话, or remove both of them, "需要帮忙告诉我", Chinese sentence always like this ＝。＝，it seems hard for foreigner,