Star Schema: In a star schema, the fact table will be at centre and in connected to dimensional tables. The tables are completely in Denormalized Structure. SQL queries performance in good as there are less number of joins involved. Data redundancy is high and occupies more disk spaces.
Snowflake Schema: is an extension of star schema where the dimension tables are further connected to one or more dimensions. The tables are partially denormalized in structure. The performance of SQL queries is little bit less compared to star schema as more no. of joins are involved. Data redundancy is low and occupies less disk space compared to star schema.