Standards are mandatory activities, actions, or rules. Standards can give a policy its support and direction. They can be externally or internally mandated.

Standards may specify how hardware and software products are used, and in terms of databases, how to database server may be used. Standards define specific parameters and procedures which are implemented in a uniform manner across all other implementations. Like a internal Standard server installation document. Or wearing the company badge at all times with in the company. etc.

Along with Standards come Guidelines and procedures to achieve and support the directives in standard policies.

Baselines : can be referred to a point in time data collection that is used as a comparison for future changes. Baselines are formally reviewed and agreed upon by the Management and technical team. Hence a Baseline result is a consistent reference point.

Like we define baselines for our Servers and systems. Which are then used to compare those values against future changes to the server or systems for analysis purposes.
But remember baselines are defined just after the assessment of the risk and security procedures are in place and the environment/server/system is set to start production life.
Consider Baselines as minimum level of protection required on a server/system.

Guidelines: are recommended actions to be performed on a system. They can define how the action are to be performed. Like while creating a database, you need to open a Ticket for the production team to let them know of your request. in return the production team will come back with the request change complete or more questions. get approvals etc..

Procedures: are the most specific and most detailed documents. They define the actual step-by step implementation of mechanisms to meet the requirements of the policies. Procedures are linked to specific technologies and devices and could change as requirement /standards changes based on the application change.