AWS Glue table schema comments vs no comments

Question

I created Athena tables from a bunch of csv files living in S3 using an AWS Glue crawler, why does some of the table schema's contain the Comments key and some not? Even though no Comments are defined?

 {
    "Name": "dead_sec",
    "Type": "string",
    "Comment": ""
  },

VS

 {
    "Name": "dead_sec",
    "Type": "string"
  },