Why there is an article in the first sentence is as FumbleFingers states; also:
Left by itself, respect is a noncount noun and cannot form a plural. This means respect can't be counted, just like weather is a noncount noun. Example: We don't say, "I have 13 respects for my Uncle an 93 for my Dad," or, "26 weathers will be arriving tomorrow." You either have respect for someone, or you don't. You can't count respect. You have weather. No article needed.
Confusion comes when respect has been made into a compound subject, like "grudging respect." For reasons Fumblefingers state, speakers of English treat respect as no longer general, but has become a specific kind of respect; a grudging respect. Like, some today say "We're in for a bad weather today," the article is not necessary, but people do it anyway today.
Rules for count nouns that can form a plural (like orange/oranges - an orange/the oranges) an article is required. "a" for consonants [a hotel; a car] and "an" for vowels [an elephant; an electric typewriter, etc., include those that sound like vowels {an L} sounds like "el" when spoken.]
Cheers!
Hope this helps.