How does heat generated by metabolism differ compared with heat generated through exercise?
First, you have to convert your numbers to the same units for any comparison to make sense. Consider that the average human body has a surface area of about 1.8m$^2$ and a volume of about 66L = 0.066m$^3$. Then your numbers are equivalent to 2230W metabolic heat and 1050W exercise heat for an average person.

The value 2230W for basal metabolic rate (from Table 1 of the Bagum et al paper) is nowhere near what's measured in practise. Basal metabolic rate ("metabolic equivalent", 1 MET) would be 105W for an average person according to the wikipedia page you cited, which equals 2150 kcal / day. That's about the recommended daily calorie intake, so it makes sense. I don't know where their value of 33,800 W/m$^3$ for "metabolic heat generation" comes from, perhaps it's meant represent something else (can't say I understand the article) but it's not the metabolic rate for an average human tissue.