The pyramidal framework of hierarchy:

It is no longer common in practice.

Is the most complex to manage.

Is typical of public organisations.

The horizontal framework of the hierarchy:

It is most common and recommended for small and agile organisations.

It implies a peer-to-peer relation across all levels.

It is recommended for large organisations to reduce internal complexity.

The format of the communication relates to:

The way the content is introduced and presented to the interlocutor.

The clarity of the message.

The relevance of the content.