There are many makers of 4 stroke engines with prices that vary by 10K. How do I know which one to choose? The Mercury Verado looks very nice with a 275hp model around 20K. I wanted a Yamaha 250, but it is 30K. Any comments?
First, check out both dealers. You are going to need service and support and the dealer with a better rep is going to make you happiest, regardless of what engine you buy.
Next, itemize what comes with each motor. What else is neccessary to install it. Examples would be cables, control box, wiring harness, key switch, etc. (Does that Verado quote include teh required power steering?)
Next, get aboard boats equipped with each engine--the selling dealers should arrange this if they want your business. See what controls and gauges you are most comfortable with? See what cowling you find easier to remove--you need to check the oil on a 4-stroke, unlike a 2-stroke. Etc
After doing all this, you will find that yes, there is a difference.