It can be difficult to tell the difference between a cold and hay fever. If you have hay fever, your runny nose will likely have a thin, watery discharge, and, despite the name, you will not have a fever. If you have a cold, you may have a thicker or yellowish discharge from your nose, and may have a low-grade fever. Hay fever symptoms can begin immediately after you are exposed to allergens like pollen or animal dander , and will continue as long as your exposure continues. A cold will most likely begin a day or two after exposure to the virus, and can last a few days to a week.
Allergic rhinitis may also be classified as Mild-Intermittent, Moderate-Severe intermittent, Mild-Persistent, and Moderate-Severe Persistent. Intermittent is when the symptoms occur <4 days per week or <4 consecutive weeks. Persistent is when symptoms occur >4 days/week and >4 consecutive weeks. The symptoms are considered mild with normal sleep, no impairment of daily activities, no impairment of work or school, and if symptoms are not troublesome. Severe symptoms result in sleep disturbance, impairment of daily activities, and impairment of school or work. 
The main difference between the injection and the tablet form is that once you've had the injection, there's nothing that anyone can do to stop the steroids leaking into your blood stream. If you do suffer any side effects, these may last for up to three weeks. If you're taking tablets, stopping the treatment will usually cause the symptoms to cease within twenty-four hours. In a nutshell - the injection is faster and more convenient than the tablets, but if you're unlucky enough to suffer side effects, you'll be stuck with them for longer.