Bundle vs. Group product

These are my thoughts on this brain twisting question. For the sake of understanding let us analyse them in different view point

Examples

GP

Furniture Set, different size of knife set

BP

Personal computer system, Human Being (in literal sense, just for a fun :).)

Self Existence

GP

This is somewhat zero in my opinion. GP is just like a cover that holds the real products. So the products which constitute GP are the real existing products. GP is just a platform where we can see a couple of related products together

BP

BP has self existence. It is closely integrated with its constituting products. Constituting products when acts "together", they become a new fantastic product

Constituting products

GP

They have self existence. We can buy them individually via group products if we desire. In another word we can treat them as single products

BP

They may or may not have self existence. In order to make it more clear, suppose our BP has made 2,3 options are as required. This will resist us to buy only one option from BP. Each options are products itself. So BP is not a platform to buy an option individually, rather each individual options are acts as decision points for the final product

Appearance

GP

GP always looks like a group itself. For a GP, we will always more concentrate on each individual products that is constituting it.

BP

BP looks like a single entity and constituting product will look like its different part. The best example is human. Human has different body parts and they are different in shape and functionality. But when they "stay together", they become another entity which can function in different ways. This is obviously not a GP, since if we separated a body part, it will ruin the appearance, gesture of the actual human

customization

GP

For GP, customization is limited. Means customization for GP depends upon the selection of individual products and its count. For eg, take knife set. One select 2 medium knife and 1 large knife while another one select 1 medium and 2 large. What is the big difference ? At last they are just knifes :)

BP

For BP, customization is limitless. We can configure bundle product with given options. Each configuration will looks like unique and will result into a unique product which has its own existence. Take a computer. When we select different RAM, cpu etc, each of the configuration really makes a unique product itself. Isn't it ?

So they are very close each other. It is very very difficult to explain what is the real difference between them. Some logical thoughts always required to differ them. In order to discriminate them, we need to observe them more. My explanation is not complete. We can add lot of points to it. But for now, these are my random thoughts. Hope it makes some sense

EDIT

In case of tennis game, let us look when should we use different product types

To sell tennis bat and Tennis ball individually -> go for simple product

To Sell tennis bat and ball together -> Go for grouped prodcts

To sell tennis bat with different size -> Go for configurable product or simple product with custom options

To sell a fully customizable* tennis bat -> Go for bundle product

customizable in the sense, we can provide different grip size, string, string strength bla bla bla etc etc etc

As far as I know, the grouped product is has only one purpose. Group a set of simple products when displaying them on frontend.
You should use grouped products when you want to show the customer that some products are part of a specific set but the customer does not have an obligation to buy the full set. The best example for grouped products is a furniture set. It was one in the sample data for ce 1.6.
You can have a table, a chair and a couch as part of the set and the customer can buy all of them or just one or 2.

Bundle products should be used when a customer can build his own product based on certain options.
But in this case some of the options can be required.
Again the best example was in the same sample data for ce-1.6. There was a product called gaming computer.
The customer can configure certain features of the computer like case, ram, cpu, hard-drive, peripherals.
The peripherals are not mandatory but the rest of them are.
For each feature they can select from a series of options that have to be simple products in the catalog. These options can have the same price as the simple product or just a fraction of the price if bought together with the main product.

When you add to cart 2 products that are part of the same grouped product you see 2 lines in the cart. When adding a bundle product with options you will see only one line in the cart.

Additional: The difference between bundle and configurable is that for a configurable product you select a value of a certain attribute and for bundle you select additional products.

Grouped Products

Grouped products allow you to create a new product using one or more existing products in your store. For instance, let’s assume you have a “Barrack Obama Action Figure” and a “George W Bush Action Figure” already in your store and you wanted to sell them as a bundle. You would simply create a new Grouped Product (let’s call it “Obama + Bush (Get Both and Spend Twice as Much!)”, then add both action figures to the group via the “Associated Products” tab.

Note: Unfortunately, you are not able to set a special “group” price directly from the product page. To offer a discount for buying items together, you will need to create a new Shopping Cart Price Rule.

Bundle Products

This product type is also known as a “kit” in other eCommerce software. This product type is ideal for circumstances where the user have to select a number of configurable options, but at least one option. This might includes products like:

Customizable Computer Systems

Customizable Tuxedos/Suits

References:

• Ref1
• Ref2