STEM Bound Student: Does ACT Science have the same impact as ACT Math?

This is a great question, and the short answer is that as long as you have a composite score within your target range as well as consistently strong performances in your relevant coursework, you don't necessarily have too much cause to worry.

In general, schools are looking at standardized test scores in their composite form as part of a larger "academic profile" indicator. A more important part of this metric is your overall performance in school (as measured by GPA, rigor of schedule, etc.). This means that as part of the holistic admissions process, standardized tests are more of a thresholding mechanism than an area for deep consideration.

In addition, schools are aware that students typically change their majors at least once between application and graduation, so they tend not to put to much weight on your stated field of interest beyond trying to understand you as a cohesive, 3D person (which is why you should always write about a major you're actually interested in rather than one you think will be more impressive or easier to apply into). As such, admissions officers will likely take a look at your scores in sections most relevant to your stated area of study, and they will certainly assess your performance in coursework related to this field, but this is largely to check for cohesion of the application.

One last thing to note: if you retake the ACT and perform better on the science section in your retake, almost every school will superscore the test -- that is, they will consider the highest score for each section when assessing your composite score. So, if you are thinking of taking the test again, there could be a real benefit to studying especially hard for the science portion to improve that score.

I hope this helps, and best of luck in the rest of the admissions process!

There are obviously exceptions to this, such as schools with a rigid structure that makes it difficult to transfer between majors once you arrive on campus (e.g. it is difficult to transfer from Penn's College of Arts and Sciences to Wharton).