Difference between Google Interactive Media Ads(IMA) and Google AdMob

I read about Google IMA and Google AdMob and as per my understanding both are used to used to deliver Ads. The differences are that:

1) Google IMA is generally used when video Ads are required which I believe is not supported by AdMob.
2) AdMob is generally used when only Banner Ads are required, as it is simpler to integrate than IMA SDK.
3) In case of IMA, a VAST server is required to return Ads, but in case of AdMob, an account with AdMob is need to create the AdUnits.

So my questions are:

1) Is my understanding regarding the differences correct?
2) IMA appears to be a superset of AdMob in terms to features since it can also support banner Ads. Is that correct?
3) Is there any other reason to use AdMob instead of IMA apart from simplicity of integration and not requiring a VAST server?

To address your questions, let me first talk about what each SDK does in short. If you have any questions, feel free to ask:

• The Mobile Ads SDK (Android, iOS, and a plugin for Unity) serves ads (banners, interstitials [static or video], rewarded videos, and native ads). Ads can be served from AdMob, DoubleClick for Publishers, and others via what is called mediation. For ad networks not on that list, you can write a custom event to manually mediate with it.
• The IMA (Interactive Media Ads) SDK (Android, iOS, HTML5, Flash, and the mobile web) serves video-based ads. Ads can be linear (pre-roll, mid-roll, and/or post-roll), non-linear (overlay banners sitting at the bottom of the video player screen), or companion ("banners" that accompany your video ad - these are distributed outside the video player area). These ads are mostly served from DoubleClick for Publishers and AdSense.

Now, let me address your points in details:

Google IMA is generally used when video Ads are required which I believe is not supported by AdMob

This is correct in a way. Video ads are also supported by AdMob, as long as they are in the format of an interstitial. You might have seen an interstitial (a full-screen ad) with a video playing in the upper portion of the ad. That is a video ad in AdMob's sense. Some developers use both SDKs together in their app to serve both interstitial and video ads!

AdMob is generally used when only Banner Ads are required, as it is simpler to integrate than IMA SDK

As I noted earlier, the Mobile Ads SDK serves a whole lot more ad formats than just banner ads. Out of the box, both SDKs should be simple to integrate. You can check out our GitHub samples!

In case of IMA, a VAST server is required to return Ads, but in case of AdMob, an account with AdMob is need to create the AdUnits

Correct.

IMA appears to be a superset of AdMob in terms to features since it can also support banner Ads. Is that correct?

Not quite. I wouldn't refer to IMA as being a superset of AdMob / the Mobile Ads SDK. Each SDK serves its own kind of ads, so depending on your monetizing need, you can pick the one you prefer (if not both).