To add to what Acey said.
Here is the 737-8 Max of Westjet
https://4.bp.blogspot.com/-EgVIE4FdF...00/image1.jpeg
https://c1.staticflickr.com/5/4245/3...bcd2fd79_b.jpg
Here is a 737-800 with scimitar winglets
https://cdn.jetphotos.com/full/6/16032_1479095848.jpg
https://farm1.static.flickr.com/196/...616b845b4d.jpg
As Acey said, 2 key things that really stand out. The chevrons on the engines, and different tail cone. The tail cone is more pointy on the 737-8 Max