“Though” vs. “although”

Question

Can we use though and although interchangeably? Somebody told me that the difference is that though cannot be used at the beginning of a sentence. Is that the rule?

Answer 1

Though can definitely be used at the beginning of a sentence, and has a long history of doing so. Consider Isaiah 1:18 from the King James Bible:

Though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool.

TheFreeDictionary.com cites this usage rule:

Although and though are interchangeable as conjunctions, but to start a clause, use although.

However, this seems overly fussy and prescriptive. Consider the following:

I went ahead and chopped all the wood, though no one told me to.

You left without your luggage, though I can't imagine why.

Those sound to me like perfectly fine English. They would be perfectly fine using although as well. That, to me, feels like interchangeability, pure and simple. In fact, I can think of no examples in which though cannot be used interchangeably with although. Though your mileage may vary.