Is this stem stitch or outline stitch?

I am not sure anymore, but I am also not worried about it.
I try not to worry too much about the names but rather the resulting look of the stitch. Because of the influence of the twist of your threads you will see a difference between split stitch and outline stitch.

I experimented by practicing the stitch with the working thread held above (pink thread) or with it held below my guideline. I also played with different guideline curves, testing clockwise (top two lines) versus counterclockwise lines. For all of the lines I worked from left to right and I kept my hoop positioned as shown in the photo.
My findings:
- In general, I prefer the look of my lines when I hold the working thread below.
- The curve of my line isn't so important when I keep my stitches small.
- Being consistent is most important. Pick a version and stick to it, always stitching from left to right and starting with your hoop in an upright position rather than upside-down.
I encourage you all to try this experiment yourself! Keep your finished work and label it in a way that makes sense to you. When a pattern calls for stem or outline stitch refer back to your experiment to decide which version you want to use.