Generic answer is "it depends" when it comes to calories. For strict absolute weight loss, less calories means more weightloss. But if you are doing physical activities (not just leading a desk job lifestyle) you want certain macro nutrient quantities. If you do lots of cardio-esque stuff, then you want more protein in your diet. Same goes with people who lift weights and want to maintain strength; having low protein means you don't repair as fast as a high note, and as a low note you go catabolic regarding muscle to fuel day to day activities. If you're a keto kid, this is an actual serious concern -every- day you're in keto.
If the content of your calories is empty shit like Starbucks or pasta (and I f'n love pasta, but it isn't a good idea for people on diets in general) then the content is actually more important than the total amount. But if you are even remotely balanced, ie eating fats/proteins/carbs to varying levels but not wholesale axing one or another? Yeah, the number of calories is waaaay more important than the specific macro counts.
Your bread issue is a non-issue. If 50 calories (lets say 100 since you're using two slices for a sandwich) is a legit issue with your weightloss, then something else is way off. Like either working out too much on an incredibly limited diet or the rest of your macros are incredibly anorexic-ish. White bread has effectively zero satiation attached to it, so while the absolute caloric value doesn't matter at all, you're probably going to feel hungrier eating 100g of calories in white bread vs. 100g of calories in wheat bread. In the end, if you consume x calories, you lose if x is less than whatever it takes to keep you alive/maintenance calories. The "quality" of calories mostly impacts how you feel about that intake, and whether or not you feel hungry or not. This is where the keto diets come in, as since you skip "empty" carbs, you end up with a lot of longer digesting food in your system. This has zero impact on weightloss in a vacuum, but if the satiation aspect keeps you from eating more, you will notice a downward trend in weight as long as the net calories are negative.
TL;DR: for weightloss, total calories are the most important statistic, unless you have a legit medical issue that requires certain macro nutrient combinations/ratios.