There are many words in the English language which are routinely interchanged. Whether one accepts these “switches” depends upon whether the person is a semanticist or a grammarian. Semanticists normally are concerned with the word’s meaning, while the grammarian deals in proper usage. I suspect as the world has now moved to the 140-characters message the differences appear impractical and perhaps a bit nonsensical. However, there are those who “toe the line.” For example…
A person should use can meaning the “ability to complete”; whereas, may indicates “permission.”
Because is used to indicate a “reason/cause”; whereas, since refers to “time, meaning between then and now.”
In behalf of means “for the benefit of another”; whereas, on behalf of means “in place of.”
Use between when “two people/places/things are involved.” Use among for “three or more.”
Use amount for an “indefinite quantity that cannot be counted.” Use number for quantities, which can be counted.
Ensure means “to guarantee or to make certain”; whereas, insure means “to make safe from loss or harm.”
Hanged means to be “executed”; whereas, hung means “to place.” Do not use hung when referring to an execution.
Likewise, dragged means “to pull with great effort,” whereas, drug refers to a “medication or chemical substance.”
Fewer is used for things, which can be counted, whereas, less is used for bulk or quantity.
Convince means “to cause one to believe.” Persuade means “to cause someone to do something or take action.”
Disinterested means “not having taking sides or making a choice,” whereas, uninterested means to “hold no interest in.”
Although means “despite the fact that.” The word while means “during that time.” Do not use while when the purpose is to show a contrast.
Anxious means to know “concern”; whereas, eager refers to indicate “impatient desire.”
Each other should be used to when two people/places/things are involved; whereas, one another should be used for three or more people/places/things.
Farther refers to distance; whereas, further refers to degree or extent. (i.e., We should speak further.)