Is DBT case sensitive?

I have not got any specific answer to this question. Can any one, please, help me in understanding this.
In our .yml files will it be different if the table names are in lower or upper case?
I know, snowflake is case sensitive, so does it mean we have keep in mind when our dbt queries hit Snowflake? For example, if I want to use a column( from a Snowflake table) in my query in .sql file so do I have to use : where UPPER(columnname)=‘ABC’

I think no.
By default Snowflake stores unquoted column names in uppercase. If any unquoted column is used in a query in lowercase it automatically converts into uppercase.