The pyramidal framework of hierarchy:

It is no longer common in practice.

Is typical of public organisations.

Is the most complex to manage.

The horizontal framework of the hierarchy:

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

It is recommended for large organisations to reduce internal complexity.

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

The format of the communication relates to:

The clarity of the message.

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

The relevance of the content.