Difference between "As" and "Like"

[proxer]

* * *

Today shire horses are seen more and more in
their traditional role _________ workhorses.

A) alike
B) as
C) like
D) as if

* * *

The rewsnA is bi. My question is that what is the difference between "like" and "as".

This question was quoted from Cambridge Prep. book page 280 q.num. 15.

The explanation in the book is shortly : "as" is a preposition used to indicate the function of horses. "like" is a preposition which indicates a manner or comparison.

[Nemoftu]

* * *

Today shire horses are seen more and more in
their traditional role _________ workhorses.

A) alike
B) as
C) like
D) as if

* * *

The rewsnA is bi. My question is that what is the difference between "like" and "as".

This question was quoted from Cambridge Prep. book page 280 q.num. 15.

The explanation in the book is shortly : "as" is a preposition used to indicate the function of horses. "like" is a preposition which indicates a manner or comparison.

Hi Proxer, I think the main point here isn't such kind of explanation. The words like and as can both be used to talk about things that are similar. But note that like is similar to a preposition, and comes before a noun or pronoun (This tastes like lobster). As is a conjunction, and comes before a clause, or a prepositional phrase (When in Rome, do as the Romans do).
In this case, your original sentence is:
Today shire horses are seen more and more in

their traditional role _________ workhorses (are). ---> a clause
So it must be "as".
Note:
In American English, it is common to use like instead of as in this way, but it's not normally thought to be correct in formal English.
Like is used informally in the same way as 'as if/though', especially in American English, but it's also not normally thought to be correct in formal English.

[Erin]

Nemoftu has given a good explanation, so I can't add much. You might want to check out another post in the forum about like vs. as.