比 vs. 跟 for comparisons I've read a lot of answers to questions about 比 but I didn't see anything about 跟.

I recently had a class where the 老师, in three days, three hours a day, FLEW through enough material for two weeks if not more.  But he also gave me lots of printouts of what we would have gone through in his normal (one month) class.

We spent ten or fifteen minutes comparing things.  This is not a "state a grammar rule and then make sure they can apply it" class.  More of a "lots of input until it sinks in" class.  Which is actually a good method if you have time to give enough input.

ANYWAY, here are four things from the comparisons¹ paper.  I have put in the nouns and adjectives randomly where the paper had blanks to fill in.  Is there a different in connotation or denotation?

你的衬衫**比**我的衬衫好看。
你的手机**比**我的手机好用。
你的衣服**跟**我的衣服都便宜。
你的房子**跟**我的房子都贵。


I also notice on this site, examples of comparisons¹ are different and shorter than in these handouts, which had only these two formats.

¹As the answers reveal, it wasn’t actually a paper of only comparisons.
跟 in "你的衣服跟我的衣服都便宜"。 and "你的房子跟我的房子都贵"。is not 'compare to' but 'also/and' 

In face, 跟 doesn't contain meaning of 'compare to' . 

You thought so because in [X 跟 Y 比] ("X compare to Y" ) structure '跟' is always paired with '比'


  你的衬衫比我的衬衫好看。- 比 = compare to 
  
  你的手机比我的手机好用。- 比 = compare to
  
  [(item A) 比 (item B) + (adjective)] = [ (item A) compare to (item B) is (adjective)]


~


  你的衣服跟我的衣服都便宜。- 跟 = and 
  
  你的房子跟我的房子都贵。- 跟 = and 
  
  [(item A) 跟 (item B) + 都 + (adjective)] = [ (item A) and (item B) are both (adjective)]


~


  also notice on this site, examples where the adjective is at the end. There were none like that in the handouts. All were in these two formats.


But the adjective is at the end in this two formats too. 好看, 好用, 便宜 and 贵 are all adjective

~

Add 跟 in a comparisons structure instead of using 比 alone:


  (你的衬衫)跟(我的衬衫)比, (你的衬衫好看得多) 
  
  take (item A) and (item B), and compare, + (opinion/ statement)


Another way to use 比 in a comparisons structure is  "compare to A, Y is (opinion/ statement)":


  [(比起)(我的衬衫), (你的衬衫)(好看得多)]
  
  [(compare to) (A), (B) (opinion/ statement)]