I can't find the exact understanding between cloudflare worker kv and dynamoDB in aws, Can anyone make it clear in simpler ?
Although there are some similarities (ie. both DynamoDB and Worker KV are offered as managed services) I would say they are more different than they are alike.
Worker KV are always eventually consistent whereas DynamoDB can be strongly consistent for read after write operations.
DynamoDB has additional capabilities such as local and global secondary indexes allowing you to have different access patterns for the same underlying data.
Workers KV is heavily optimized for reads with infrequent writes, whereas DynamoDB doesn't have the same limitation (though DynamoDB also does better at reading data than writing in terms of throughput).
DynamoDB also has other features such as stream processing which allows you to do out of band processing in reaction to changes to the data stored in the database.
I'm not sure about the security model for Workers KV but DynamoDB allows you to configure strict access policies to the tables.