Difference between Projects, Deals, Quotes, Jobs

A Project is a planned and organized activity/mission/goal that needs to be accomplished, generally by a team of co-workers.
It has a set of tasks assigned to each team member.
You can track the status, completion %, dates and milestones of the project.
It can be linked to contacts, companies, notes, files, events, forms, and to a geographical location on a map.
You can also specify financial elements: a budget amount and products consumed during the project, which are used to generate a quote or invoice.

Deals are relevant in the Sales process: you create a sales Opportunity for a customer.
You can track the different Stages: incoming, qualified, closed won, lost, etc…
You can add an estimated sale Amount, which gets into the pipeline displayed in the Sales Forecast, with a probability.
It can be linked to contacts, companies, products.
You can create a quote for the customer.
You can also link a project which corresponds to work that needs to be accomplished for the customer related to the deal, once it is closed, or in order to close it.

Quotes are used to send an estimated cost of a list of products or services to a potential customer.
They can be exported as a PDF and sent by email to the client.
Reports allow to track amounts quoted or invoiced.
Different statuses: Confirmed, Invoiced allow to track payment related to quoted amounts.

Jobs are field-related tasks scheduled and assigned to a team of co-workers. Typically used for deliveries, maintenance and repair teams. Functions include:
A Scheduling Calendar to assign pending jobs to each team member.
Tracking job assignment and execution: who has checked in or out of a job, pauses, job duration.
Geolocalization on a Map and Optimization of the Route between waypoints.