The science-related questions on the new SAT are more multidisciplinary the questions on the ACT science section. They ask you to combine your skills in the main subject area covered by the section with an ability to read data. You won't see elaborate technical descriptions of experiments with lots of numbers and variables.
You'll find science-related questions on the Math and Reading sections of the SAT in different forms. For SAT Reading, you'll see a passage dedicated to a scientific topic followed by a chart or graph that displays relevant data. You'll answer standard questions about the reading as well as questions that ask how the data in the chart relates to the claims in the passage. Some questions have similar formats to ACT science questions, the only difference being that they will ask you to consider both the data and the statements made by authors in the long passage to find the correct answer. In the the Reading section of the first new SAT practice test, I count only six "science" questions out of 52 total questions.
For Math, you'll find science-related questions in the second section (the one that allows the use of a calculator). Most of these just involve reading charts and graphs accurately. They're straightforward math questions that use scientific context to make them more relevant to real-life scenarios. You don't need to know any science to answer these questions correctly.
"Science" questions on the new SAT will test your ability to apply the same skills you've always been asked to use on the Reading and Math sections, just in a different context. They may take some getting used to (which is why you should definitely take a practice test and see how you do), but they shouldn't be too much of an added challenge even if you struggled on ACT science.