Derek already answered the question well, but let me add an important difference between English and Japanese about comparisons. While “より X” means “more X,” simple “X” can also mean “more X.” In other words, unlike English, the comparative degree does not have to be made explicit in Japanese. The adverb より clarifies or emphasizes that it is about a comparison.
For example, suppose that Shun and Takumi are comparing their heights. (○ before an example means that it is correct, × means that it is incorrect, and ? means that it is questionable.)
○ 駿の方が背が高い。 (しゅんのほうがせがたかい。) Shun is taller.
○ 駿の方が背がより高い。 (しゅんのほうがせがよりたかい。) Shun is taller. (with emphasis on the comparison)
○ 駿は拓海に比べて背が高い。 (しゅんはたくみにくらべてせがたかい。) Shun is taller than Takumi.
○ 駿は拓海に比べて背がより高い。 (しゅんはたくみにくらべてせがよりたかい。) Shun is taller than Takumi. (with emphasis on the comparison)
When the particle ～より is used to signify the second member of the comparison, the adverb より sounds weird because of the repetition of the same form より.
○ 駿は拓海より背が高い。 (しゅんはたくみよりせがたかい。) Shun is taller than Takumi. (より in this example is the particle.)
? 駿は拓海より背がより高い。 (しゅんはたくみよりせがよりたかい。)
I do not think that the adverb より can be used with the amount of the difference:
○ 駿の方が 5 センチ背が高い。 (しゅんのほうがごセンチせがたかい。) Shun is taller by 5 centimeters.
× 駿の方が 5 センチ背がより高い。 (しゅんのほうがごセンチせがよりたかい。)
Historically, the adverb より arose from the particle より, and the adverb より was first used in translations from European languages in Meiji era (according to Daijirin). Therefore, excessive use of the adverb より may result in translationese.