This is a question for which the answer (at least on the management side of the equation) has evolved greatly over the last 15-20 years and is probably still evolving today. These are, of course, broad generalizations (there are always exceptions, including people in specialized corners of the business) but I guess I would say that an agent tries to get work/opportunities for their clients and then make the best possible deal for the client on said opportunity. Agents are regulated, bonded and generally take a 10% cut of the deals they do for their clients. Each agent tends to represent more clients than each manager does - and they tend to have a broader handle on what jobs are coming open around town (especially at the bigger agencies, where they can more easily leverage their size in order to track the truly mind-boggling number of projects that are constantly moving on to and off of studio and network slates).What managers do is a bit more fluid. Many managers have a hand in everything their clients do - they are more likely to dive in and spend a lot of time working with clients on developing projects (in the case of writers and directors) - and may be involved in many of the other personal and professional aspects of their lives. Managers are not technically supposed to procure work for clients, but most still try to do so and their clients are very happy about that fact. Sometimes managers have a hand in the deal-making process, but they have to be careful to leave most of the nitty gritty of the negotiations to the agents and lawyers. Managers are not regulated - anyone can hang a shingle and call themselves a manager - and they are allowed to be producers on their clients' projects, whereas agents are not. Managers' commissions are somewhat more variable than are agents, and they can have different deals with different clients on what percentage of the clients' income they receive - for instance, an incredibly successful client will often pay the manager a lower percentage of their income as a commission. If a manager is producing a client's project, they generally do not commission the client on that deal and instead receive compensation in the form of their producer fee from the studio/network/financier/etc.