Most of the concepts in this post have been said better elsewhere, but I find myself reflecting on them with every new client so it makes sense to write it down. So - working from top down...
A "Vision" or "Mission" statement is a formal acknowledgement of the purpose of an organisation. It describes why that group of people are working together and what they hope to achieve.
There is a difference between "Vision" and "Mission". The former is a target and relates to an outcome-based enterprise. The latter is a process and is used by a system-focused organisation. You may have both but it is an red flag that the point of the group is not clearly understood.
Each division of the whole, the different business units, are also groups of people working together and hence should have a defined purpose - one that aligns with the larger organisation. These need not be the same type: Project Management is naturally results-based and a project needs a vision, while Operations are an on-going activity and hence should have a mission.
If a Vision or Mission defines a direction, the next lower level is defining how to progress. These are defined by "Strategies" or "Goals" - again, system or outcome focused. While it makes sense to have strategies to reach a Vision, or goals while carrying out a Mission, making a clear connection to purpose is easier if the focus remains similar.
The next level I call "Tactics" and
"Targets", although I've heard many different terms across different
companies- or even with the single one. Targets should comply with the
SMART principle: Specific, Measurable, Achievable, Realistic and
Time-bound. (Tactics do as well, but I am not sure what the appropriate
acronym is for a process-based activity).
As a statement of purpose, the Vision or Mission should have direct relevance at every level of the enterprise and provide a sense of connection to the whole. The tactical level is where day to day work happens and therefore where most employees live. To create a sense of belonging and employee engagement comes from the link back up to the higher purpose.
I've found that many organisations have a Vision which new starters hear during induction but which has no relationship to their actual work. When the enterprise's reason-for-being is a mish-mash of buzz words or generalities, ignored by internal staff and unknown by externals, it becomes quite difficult to make sure activities and capabilities are aligned.
Executive managers know they need a Strategy to back up their Vision and, indeed, I've found most business units also have a rough plan they call a strategy. Often they are generated by highly paid consultants, are about five years old and are stored somewhere on the corporate "G: Drive". Tactics appear as "business processes" and can be represented by the ad hoc behaviours that employees actually carry out, while Targets are only mentioned in Sales meetings and Performance Reviews.
In short - lip service is paid to these mechanisms for getting people working together in a single purpose; which is, after all, the primary reason for an organisation to be created, but the techniques are rarely followed in practice. This is why (or at least one of the main reasons) different parts of an organisation often seem to be pulling in different directions.
In my position this is usually stated as "IT do not support the business needs". More correctly, either IT or the Business Unit (commonly both) strategies, if they exist, do not align with the corporate purpose. Or they align with different interpretations of the corporate strategy. In either case, the Vision or Mission is not being clearly communicated to those who are supposed to implement it.