line interactive UPS Vs Standby UPS

I would like to know the difference between the two.

Can anybody help with this.

I bought Powersafe UPS 1000Eco 1kva.

After complete discharge. I again connected the UPS to power 15hr while I was using PC simultaneouly.

After 15hr current went it given me the backup for 7min.

According to powesafe 1kva ups lineinteractive.

CAn anybody help me..