In the UV editor, I flipped my image by going to image > flip > horizontally, since it looked inverted on my object. I then adjusted my UV map to how I wanted them to be projected on the faces of my objects. They look fine in the viewport, but are mapped completely differently in rendered mode. Why is this? do I need to update the UV mapping separately for the rendered display? If so how do i do it.
I suggest to save the image you flipped and try to render again.
Sometimes, edits in the UV Editor won't reflect in the 3D Viewport unless you enter and exit Edit Mode. You can also try that.
It is possible for the 3D Viewport to use a different UV map than the one used in rendering, but that's only if you have multiple UV maps. I assume that's not the case.