Is this a 737-800 or 737 MAX 8?
The MAX is re-engined with more efficient CFM International LEAP-1B powerplants, aerodynamic improvements (most notably split-tip winglets), and airframe modifications.
Checking what the new features are allow for easier identification. The photo you have lacks the split-tip wingtip device. And when the viewing angle is tricky, like the one below, the engine chevrons would be another thing to look for (only available on the MAX series).
I would suggest using the highest resolution photo available and zooming in, as your aircraft ID questions all seem to have visible tail numbers, though some are hard to make out once they've been scaled by the Stack Exchange uploader.