Is Lenovo drive interchangeable with Dell?

Even if you don't want/need anything on the old disk I would still recommend you get an enclosure for it so you can use it as an external drive. Assuming the laptop the drive came out of isn't ancient, the drive will be a 2.5" drive so it won't need an enclosure with a power brick but can be powered via USB. If the replacement laptop has USB 3.0 ports, get an enclosure that supports USB 3.0 and data transfers will be much faster. Something similar to this: Sabrent Ultra Slim USB 3.0 to 2.5-Inch SATA External Aluminum Hard Drive Enclosure

An external drive can be used to do backups or can be used to hold large files such as videos in order to keep the drive on your laptop from filling up.

If you want to save the data on the HDD, you could put it in an external drive enclosure and access the data that way. Get one that doesn't require a power cable, just USB.

Thanks for the replies. I hadn't thought about the BIOS and hardware drivers. Duh... Should have known better. The data is not a problem. She had Windows 8.1 set up just like she wanted it. I've got a copy of her favorites on a USB stick. But as you know you can't copy the tiles over from one computer to another.

I agree with sch911 - even if it fits and connects and is detected by the BIOS, it probably will not boot. Why are you thinking about installing the drive from the Levono to old Dell? If there is data you want off it, then something like this cable would allow you to transfer/back up anything on that drive before formatting for other uses. Otherwise, spend $50 for a 120GB SSD for whatever OS you like. Use that other drive for storage via USB.

Fit yes, boot probably no. Different hardware, different drivers, etc...

But it could be re-formatted, windows loaded and made to work. But you would still lose what's on it.