US1J or avalanche diode?

Good afternoon~everybody

Thank you for spending time to read my post.I’m so happy when I found this forum cause I know there are someone here has ability to help me out .I met some questions when I am working on a school project about an electronic circuit which need to use diode–US1J.
Here please give me some time to state my problems cause English is not my first language and I’m poor in it.
Well,please look at the following picture:
circuit
In this circuit,there is a US1J. But I found that it recommend that using STTH1R06 here cause that it’s avalanche diode according to the information.I would like to know:
1). Are there any difference between avalanche diode and recovery diode?
2).Can I use US1J here ? This is USIJ’s datasheet: [url]http://www.kynix.com/uploadfiles/pdf65976/US1J-E32f5AT_901593.pdf[/url] .

Your help will be appreciated!