Some of this info is from the Merriam-Webster. "As for" means "in regard to" or "concerning" Ex: "He's here. As for the other people, they'll arrive later." However, it would sound weird to say "He's here. Concerning/In regard to the other people, they'll arrive later." I think you would use "As for" when you're shifting focus (in this case, shifting focus from he, who is already here, to the others, who will arrive later). "As to" means "about". Ex: "I'm at a loss as to how to explain the error." Ex: "There is a disagreement as to the causes of the fire." Ex: "I remained uncertain as to the value of his suggestions." It's hard to explain the subtle difference. "As to" is more formal than "about". You could replace "as to" in any of these sentences with "about" and not change the sentence structure. I would actually say "about" for the second two sentences, not "as to". I think the biggest difference is formality and they are interchangeable, but there are probably some certain circumstances where "as to" works better. Because you could replace "as to" with "about" in these sentences, you could also replace it with one of "about" 's synonyms (regarding, concerning, in regard to, etc.). "As to" has another meaning. It can also mean "according to" or "by" Ex: "The eggs are graded as to size and color". If you used "according to" or "by" in this sentence, they all mean the exact same thing. From the dictionary: In terms of means with regard to the particular aspect or subject specified. "replacing the printers is difficult to justify in terms of cost" I hope this helps! A lot of these are really similar and I'd say the only way to fully understand the nuances and just intuitively know what sounds right is to practice English! Listening, speaking, etc. Of course, you can study, and read what I've written, and that will definitely help, but to just intuitively know, speaking and listening are what will help you!

Some of these are synonyms, and some means slightly different things. I think one of the only ways some of them are different is the exact sentences you would use them in, and just depending on what you like to say. Some of them are also a little more formal. Here are the differences I can find and some examples. "About" is probably the most general. You can use only "about" in many circumstances. "I was talking about the game." For this example sentence, you would probably never use any of the other terms you listed. They would change the meaning a little bit or just wouldn't work. "I was talking concerning the game". You could probably say this, but it sounds awkward and I don't think it would be proper grammar. Rather, you would change the structure of the sentence to be "What I was talking about concerned the game." This is a much more formal way of saying it than if you used "about". (About is the most casual and you will probably use it the most.) When you use the verb "to concern" in the ing form (concerning), it is the same as "regarding". "We have a problem concerning tomorrow." "We have a problem regarding tomorrow." To summarize: About is the most casual. It can mean the same thing as "concerned" or "concerning" or "regarding", but to change that word you probably have to change the sentence structure. "Concerning" and "regarding" are basically the exact same and to switch between them you don't have to change the sentence structure. You wouldn't ever use the past tense of "regarded" in this context.

Now, "with regard to", "with respect to" mean almost same thing. They mean something a little more different than the words I discussed before. If you say one of these, you need something more in the sentence. For example: "With regard to your feelings, I want to invite my friend to our home." This is means something very different than "about" or "concerning", etc. The sentence means that the person is taking someone else's feelings into consideration when inviting their friend to the house. You could also say: "With respect to your feelings, I want to invite my friend to our home." This means almost the same thing. The only real difference is the person wants to respect the other person's feelings vs. taking them into consideration. You could also say "out of respect for" for a decision that is already decided, or something else past tense. Ex: "Out of respect for your feelings, I decided not to invite my friend to our home." or "Out of respect for to the family members, the man was buried outside." This means that because someone wanted to be respectful of something, things went a certain way. You could also say "in regard to" (you probably wouldn't ever say "in respect to"). This means something similar to "regarding" and "concerning". Ex (taken from the Grammar Girl blog): "This letter is in regard to your message dated January 5." "In regard to" means the same thing as "concerning" and "regarding". It also means "about" but "concerning" and "regarding" are better synonyms because they keep it sounding formal. Some people think that you shouldn't use "in regard to" and you should use one of its synonyms instead. You will, however, hear people use it. People also say "in regardS to", but technically this is not correct. If you said it though, no one would notice or say anything, people say it with the s all the time.