Asset Type is currently used for organizational and descriptive purposes only. In the future we may add features related to different types of assets, but at this time all Regular Assets (other than those marked for reserve) are pooled together when our calculations build your plan. Many people like to enter regular asset accounts separately to more easily keep track of and update asset balances, but if you do not wish to do so, you may enter all regular assets as a single asset of any type.
All regular assets receive the same rate of return on investment, which you can set under Settings and Assumptions > Inflation and Safe (Reliable) Regular Asset Returns.