Is Boston, Massachusetts anything like Dothan, Alabama? My family and I are fixing to move there next week?

Start with not saying "fixing to". Northerners don't understand that it's an immediate future (which many languages have), and more sophisticated than standard English, which makes no distinction between the near and far future.

Second, the weather is very different. Be prepared to buy a whole new winter wardrobe.

Finally, people don't generally chat with the sales clerks when they're buying something, or with people waiting in line, etc. 

Growing up in AL as a kid, I know exactly where Dothan is. The difference between it and Boston? Night and day. I married and moved here in 1977, and currently live on Cape Cod. There is so much you will need to learn, but the most important is, do not be hurt by people who do not say hello back to you, and seem cold and unfriendly. It bothered me at first until I realized it was not intended to be mean, and it was refreshing to not have everybody know all your business, as is often the case in small towns. They are as friendly in their own way as people in AL. But then, don’t lose your AL friendliness and ”ma”am and sir”. My friends begged me to stay just the way I was in that department.  I love New England. I tried moving back to AL 7 years ago to be near my aging family, but only stayed 4 years. I missed New England that much. The staggering beauty compared to central Al, culture, diversity, schools, etc., was difficult to live without. So I am back ”home”.  It IS my home. Montgomery, AL was where I was born. 

 The dichotomy between Dothan and Boston is so ginormous, my advice to you is to do what I did. Experience it. It will take time to get use to, but worth it.  Oh yeah, one more thing. Get to know the transit system and forget Uof AL and Auburn. It’s Red Soxs, Celtics, and Patriots here. 😁

You have selected a best answer, but I will answer anyways.

I am a former Bostonian. I will guarantee you it will be different. (But I am certain you will find the differences fascinating.)

Don't fret too much over the language. If you use a southern term and it is not well understood, simply do a clarification. You will pick up the local lingo in no time. But never forget where you came from. (Went to UMass with several southern folk from Georgia. They gave me quite a positive learning experience about the south.)

You will definitely need to add to your wardrobe. Since you are from Alabama, you are set for the warmer seasons. 

Fall tends to be somewhat cooler so light jackets, heavier pants and shirt is recommended. 

Winter time you will need to invest in very warm clothing. Get thermal undergarments, tube socks, winter parka, heavy gloves at a minimum. Temps can go as low as -20 'F or -29 'C. (My winterwear included a Czech woolen overcoat, long johns, sweat pants and shirt, 2 pairs of sweat socks, military boots, trapper beanie, scarf, ski goggles, and military work gloves.)

If you are going to buy a car or own are living in a house, get a snow shovel. Be careful about your back when shoveling this white PITA.

Learn to use the rapid transit system. (Referred to as simply "The T") It will take you to most places you will want to go.  

https://www.mbta.com/

https://www.mbta.com/schedules/subway (Map of the system.)

If you use the T on a regular basis, consider getting the monthly passes. It will save you a bundle.

Cars. Get a good used car with dents already in them. (If you get a new car, you are almost guaranteed to get it scraped and dented within the first month. You will grow old.) Be wary of the d--chebags that do the safety inspections. (The most corrupt b-tches I ever met.) 

Finally something fun:  Kelly's Roast Beef...

https://www.kellysroastbeef.com/

Their sandwiches is wonderful along with their fish & chips and fried clams. Go to the Revere location. (Order and get the take out, drive the car and park at a location at the beach, then eat while watching the tide.) My family did this for decades.

The New York Soup Exchange (by Government Center... green line on the T)

http://www.nysoupexchange.com/

Quincy market: 

https://www.quincy-market.com/  (Place is just crazy. You will like it.) 

Go the museums and the aquarium. Too many to mention. But here is a few notable ones: 

https://www.mos.org/

https://www.mfa.org/  (Closed due to the pooh-bear emperor Xi bioweapon. Should re-open in September.)

https://www.neaq.org/

Enjoy the city I do miss it. 

No, those are two very different places.

Boston is very different from the deep south. 

As a southern girl who moved to New England...

Work on removing "fixing to" from your vocabulary. No one up here understands what it means.