you will find that most places, they have choices of a "meal"...like at Cosmic Ray's at Magic Kingdom, there's a BBQ Ribs meal that comes with Ribs, mashed potatoes, green bean & a beverage...and you choose the dessert (prepacked little cups...a carrot cake one or a double chocolate cake one for example) You don't pick the sides on the meals. They come with the sides listed with the meal. Or at Pecos Bills, there's a taco salad...if you order that as your dining plan meal, that's all you get...the taco salad, a beverage and your choice of which prepackaged dessert you want...and of course there's the "fixin's bar" where you can add toppings like chopped onions, , chopped tomatoes, cheese sauce, etc. But with the taco salad you don't get any additional sides like french fries (the entree is considered an all-inclusive entree since it comes with a starch--the taco shell bowl--and the taco meat--and the lettuce salad...so it's like the sides are built into the entree.)
-OR- you can order a burger meal that comes with fries and beverage...again, choosing the dessert from the prepackaged choices.
At resort counter service many of the options are also a "meal" with set components, like a meatloaf meal or a fried chicken meal. Sometimes you are allowed to substitute similar sides from one meal to another...like say the meatloaf comes with green beans and the chicken comes with corn. You can ask if they'll let you have the corn instead of green beans with your meatloaf. I've heard people get told yes they can...and no they can't.
AS for the logo sign, that can be tricky. Usually at the counter service they are designating items you can get for a snack credit...so like the hot dog would not have the dining plan logo, but the carrot cake would. Now you CAN get the hot dog as the entree on the dining plan, but not for a snack credit. So you could get the hot dog, and a bag of chips, with a soda and a prepackaged dessert cup as your dining plan meal. Or you could get a soda as a snack credit, or a bag of chips as a snack credit, or a prepackaged dessert cup as a snack credit (all will have the DP purple logo)
Clear as mud, right
When in doubt, just ask the server behind the counter, or the person at the cash register...they are all familiar with what's allowed. And it can vary from one restaurant to another.