What is the difference between acquiring projects for a small firm of 150 developer and acquiring project for a large development house with 1000 developers. What kind of difference in terms of efforts?

of course there's no one size-fits-all project management but in all cases a project is a project, the trick is finding an approach that's just right for the business,and we have to understand what project are in-house focusing on deliverables (not tasks), tasks is to be managed.

it takes some effort to design an effective communication plan, it helps getting details in time and to make sure every member knows when the project has moved to the next level.

Both of these project need to deploy and follow a well defined project management framework, such as PMI.

 Client is no interesting whether juniors or seniors developer on the project. Client is interested in having a quality product and projects goal is to deliver it. So the way to go would be giving juniors easier tasks and having senior guide them to make sure that the quality standards are met.