Thanks, that is good question. While there is indeed a lot of overlap in the basic features the difference mostly lies in the added dynamic features. 

- Steemvoter allows for automated upvotes with a customisable upvote_weight and vote_delay and requires you to trust your posting key to them. The first version of this application adds a daily upvote limit for each user and does not require the user to give up the private keys. 

- Steemauto uses Steemconnect which adds security and hosts several other interesting features which are not on the roadmap like post scheduling and automated claiming of rewards. They however offer little features when it comes down to automated upvoting of a customisable user list.

Users will be able to run the code for themselves or use the front end when its available. This keep full control to the users depending on their liking. Most of the features on the roadmap are about being dynamic , keeping track of the voting power to adjust the parameters so that users can focus on other things.