There are many types of chazakos and rovs, so it's good to define our terms before we compare them. What both of them have in common is they tend to address sefeikos, or uncertainties.
Chazaka D'MeIkara חזקה דמעיקרא
Basically, assume what was, will be. For example: חזקת כשרות, חזקת פנויה, חזקת אשת איש, חזקת איסור, or in English: something is still kosher, ...
There are indeed opinions which essentially understand certain forms of chazakah as a rov.
For example, R. Yisrael Isserlein writes in Terumat HaDeshen 207:
חזקה שאינה פוסקת שהיא באה מכח הרוב כמו החזקה אין עדים חתומים על השטר אא"כ נעשה גדול וכן חזקה אין אדם פורע בגו זמנו וחזקה שאין אדם עושה בעילת בעילת זנות דכל הני חזקות באים מן הרוב כלומר רוב בני אדם ...
Both are usually associated with assumptions and clarifications in areas we lack certainty . The difference between them is what the assumption is based on.
Rov means majority. The assumption is being based on the statistical likelihood.
Additionally, a Rov/majority can influence the status of the minority in Halacha. For example, if a small amount of ...
The terms can be used in slightly different ways (much as in the same way that the definition of "fact" changes when you compare it to "fiction" or "opinion") but one way to understand it is as follows:
A Chazaka has more depth because it inherently requires more "time" depth, more data points, to draw a conclusion.
The dice has four red ...