Oxygen concentrators dispense oxygen in almost exactly the same way that oxygen tanks do, delivering oxygen directly to the patient via the same nasal cannula or oxygen masks. However, where oxygen tanks contain a fixed amount of pressurized oxygen, 
concentrators collect oxygen from the surrounding air, concentrate it, and then deliver it to the patient, decreasing the need for replacement or refilling. Concentrators are also available in multiple styles, offering larger models for using at home or in the hospital as well as more compact models perfect for travelling.
There are many similarities and differences between oxygen tanks and oxygen concentrators, and each has their own benefits. 

Oxygen Concentrators

Instead of the limited amount of pressurized oxygen used by oxygen tanks, oxygen concentrators use a system to filter ambient air around the patient, compress and convert it to medical-grade standards, and then deliver it to the patient. These life saving machines are available in both larger home-style models and smaller portable models that are more ideal for traveling and moving around.

pros

1. Unlimited oxygen. the potential of oxygen concentrators to continuously draw in and treat air ensures that, unlike oxygen tanks, the concentrator will never run out of oxygen. this is frequently noted by customers as being one of the best features of oxygen concentrators. 
2. lightweight. because they do not rely on pressurized oxygen, concentrators do not require a dense metal tank. this means that they are notably lighter and more portable than most oxygen tanks.
3.Greater versatility. oxygen concentrators are available in a wide selection of sizes, models, and styles, each designed to perfectly accommodate a specific user need. while oxygen tanks are largely all the same, concentrators provide a greater variety of choices to ensure you get exactly what you need.
4. Up-front cost. while oxygen tanks frequently need to be refilled or replaced, oxygen concentrators use ambient air and therefore don’t require the long-term maintenance costs that tanks do. all of your concentrators costs will come up-front in your initial purchase.

cons

1. Power source required. because they do not use pressurized oxygen within a tank, oxygen concentrators must rely on battery or electric power to perform their air filtering and oxygen flow. as is the case with any battery-powered device, the available charge in the battery must be considered. if the battery isn’t charged, it will eventually run out of power and the concentrator will shut down until charged again, which could be harmful for someone who needs oxygen at all times.
2. Noisy. oxygen concentrators collect oxygen from the air and then filter and compress it for the patient. this process can often be noisy, due to the various components at work, and this is the most common complaint that concentrator users have. many newer concentrator models have been designed to reduce this noise to barely noticeable levels, but there is often still some amount of sound associated with their operation.
3. Expensive. because of the complex mechanisms, oxygen concentrators are often quite expensive up-front. while this cost is a single purchase unlike that of oxygen tanks, many people may not be able to afford the high price tag all in one chunk even though it saves money in the long-run.