Is it true that you can take your old device to the apple store and get discount ?

As you posted in the forum for pre-1998 Apple hardware, how about telling us what you you wish to give back. This link will show Apple's information on the current program to encourage recycling:

Trade in with Apple GiveBack - Apple

It says "qualified" devices rate an immediate credit that can be used for a purchase, so that is a discount. The site I linked has worksheets to help you: a) determine if the device qualifies for credit and, b) if it qualifies, it has worksheets to estimate the monetary amount.

If the device is not "qualified" they will recycle for you at no charge.

I just ran my 2010 27-inch iMac with i7 processor and it says they will give me US$180 credit for it.

Note that "old" in this community is around 20 years and earlier, so for on-topic stuff, no.