Storage space?

Storage space is mainly intended for storing contacts and associated metadata in the database. For example, if a customer adds 'red sneakers' to their wishlist, you attach this information to the contact. You can attach as much metadata as required to each contact. Each bit of metadata occupies a tiny space in the database, around 1 KB. 1 GB space can hold about 1 million metadata points.

NOTE: Storage space is a soft limit, meaning you can store more than your allowed limit as long as you are not abusing our systems.

Stream rate?

This is the rate at which you can call the Send With SES Contacts API. This API is usually called to add/update contacts and to attach/detach tags (metadata) to contacts.

For example, the 'Small Plan' has a stream rate of 300 requests/minute. This lets you do a steady rate of 5 calls per second or a single burst of 300 calls in one second or anywhere in between. The total API calls must not exceed 300 in 60 seconds.

NOTE: Stream rate limit is independent of your Email/SMS sending rate. Email/SMS sending rates are determined by AWS. For example, if your AWS SES email sending rate is 250/second, you can send up to 250 emails per second even if you are on the 'Free Plan'.

Sounds right?
Signup for the FREE PLAN.