There is a good explanation of the differences on The Induction Site.

I have a freestanding stove and like the idea that I can change it out without having to alter the countertop -- which in fact I did, not long after we redid the kitchen. Some people prefer not to have the raised back panel, so they go with slide-in.

Here is a link that might be useful: Freestanding vs slide-in on The Induction Site

Just upgraded to slide-in and LOVE the clean and polished look it gives my kitchen.

We bought a slide in - it was a looks thing only, it nothing to do with performance. Our previous stove had a huge scorch mark on the back and it really soured me free standing stoves. I love how it looks, no regrets.

Until I found this forum, I thought I had a slide-in stove, because that's how it gets into its niche, you slide it in. I've since been schooled on the difference between slide-in and free-standing, which is what I have.

Until my kitchen got its facelift, I thought the built-in backsplash (riser) of free-standing stoves looked dated. Now I've changed my mind. It's altogether possible it is a dated look, but I've decided it's one I can embrace. True, it does take up a bit of surface space, but there isn't much of a mess on the tile backsplash.

You can get free standing range without the back piece. I had a slide in JennAir and when I wanted to replace it I ended up with a new kit. Nothing fit quite right so cab modification would be necessary and then new counters - One thing led to another I ended up with an entire new kit.

I have a drop in- and it sucks! No oven space, and no storage space! I didn't pick it out- it's original to the house. I would so much rather have a regular slide in or a freestanding-- a decision I will also have to make in the next few months. The one thing that gives me pause about a slide in is potential cabinet/counter modifications and the slightly higher cost of replacement.

I learned a little too late some slide ins are meant to simply replace a freestanding range with no counter modifications while others might need modifications. I ended up with a freestanding, which is what we have always had. I like the looks of the slide in, but it might have been too much change for me all at once. If the old one had made it to the remodel I probably would have gone for it!

drop in and slide in are different. Drop in literally drops into a cabinet and has a toe kick.

Slide in is a free standing range with lips that overlie the counter top on each side. I like this look better than free standing, but it is an individual choice.

If you are going to do slide in, I highly recommend doing a standard 30" opening between the granite sides, and at least 31" between the cabinets and leave an air pocket between the cabinets. This will allow you to swap out the oven in the future, or take it with you when you move if you want.

Detroit burb, that is an excellent suggestion about making openings accommodate future appliances. I'm going to make a note of that.

The difference is mostly aesthetics. I had a freestanding Whirlpool everywhere I lived. I just went through a kitchen remodel and opted for the slide-in. The pros are the ability to accent the backsplash and hood if you want to. The cons for me, are the dials/controls being in the front where they can be accidentally turned on, and also the 'fan' that turns on and blows on you. It's not a big deal actually. But, that would be a 'con'.