Rose varieties

Introduction of new character/colour/size is possible only by cross pollinating the flowers of two different types of roses.
The resultant fruits and seeds are collected and the seeds are allowed to grow till the resultant rose plants begin to show the desired features. The combination obtained is entirely a matter of chance.
Only after this these plants are then multiplied by vegetative methods such as cuttings, layering, grafting and last but not the least is by tissue culturing.

The vegetative methods of propagation or multiplication or reproduction can only maintain the existing charactrs intact in the next generation of plants.They are just the carbon copies of the original.
For introduction of new characters or combination of characters reproduction is required.The resultant plant from two different lines is called HYBRID. The hybrid tea roses that you mentioned come in the same category.

Many of the lay people do not know that roses show pollination and fertilization and produce normal fruits and seeds. This is because these methods are undertaken only in the commmercial nurseries.