Dear H4 vs F1:
Of course, there are implications. The mere fact that the H4 and F1 are two different types of visas for the US, they have different purposes for the visa holder. As a result, the purpose of each visa constrains what the visa holder can or can not do while being in the US.
The H4 visa is for the dependents of the H1 temporary work visa holder. The H4 visa holder can not undertake employment or education in the US. The F1 visa is an international student visa for which the holder must be in the US strictly for the purpose of studies. An F1 visa holder can not take unauthorized employment in the US.
The processing of the visa is done on a case by case basis. It can take several days to several weeks. You can visit the iMahal guide on
Studying in America and Canada for more details on the requirements and process for the F1 international student visa.