Does the type of exercise matter - or does it all come down

I know that you need to change things up every couple of weeks otherwise your body gets used to the routine. My question though is does it matter what types of exercise you do or does it ultimately come down to calories burnt anyway?

My exercise of choice is swimming. I enjoy it, about as much as you can enjoy something that involves hard work anyway! It fits in to my lifestyle quite easily and it burns a lot of calories in a relatively short space of time. In addition I am often told that it's great for toning because it works so many of your muscle groups at once.

In the past few weeks I've been really bad, both with the eating and the exercise, so last week decided to kick things into high gear and set myself a two week challenge. The challenge is to swim at least half a mile a day every day for 2 weeks. I'm on day 4 today and so far have swum 4 miles in 4 days. I usually stick to breaststroke but have been adding a few laps of legs only backtroke as well just to change it up - oh my god are those few laps killer though, my muscles are screaming!!!

Already I'm starting to wonder what I should do after these two weeks though - I'm not a fan of the gym, I hate queuing for everything and feeling hot and sweaty, and feeling like everyone is watching me. Not mention my tendency to compare myself to everyone in there. I just feel like a blob the whole time I'm there - it does not help my self esteem. Plus I hate the fact that I can spend an hour in the gym and only burn about 400 calories whereas an hour in the pool and I burn 900 odd.

That said I understand as well that I can't just keep swimming all the time.

I do quite a bit of walking, but again thats quite low impact and something that I do regularly already. If it's not benefitted me or aided the weight loss so far the chances are that it won't in the future either.

Oh and because I'm working two jobs then classes at the gym are out. I just can't make the times that they're scheduled for. I'd love to do something like tennis or badminton once a week but it's not something I could do more frequently than that.

So it really comes down to the gym and the pool. My question is would I be better changing up the distances/lengths of time I swim, maybe push myself harder to swim faster but for a shorter time or try mastering the dreaded front crawl so that I can change things up muscle usage wise, or should I try to split my time between the gym and the pool even though I don't burn anywhere as many calories in the gym and don't have the free time needed to stay there long enough to match the burn I could achieve in half the time in the pool???

What do you think. I'm looking at toning as well as weight loss, although the weightloss is my motivator.

Any input from those better educated than myself???