Step 1 Enable Photo Stream on iPhone
Tap on "Settings" on your iPhone. Select "iCloud" and enter "Photos" to ensure "My Photos Stream" is on.
Step 2 Turn on Photo Stream on iPad
Follow the operation above on your iPad. But remember, you should log in the same Apple ID on both devices.
Step 3 Save iPhone pictures to iPad
Turn on "Photos" on the iPad, and select "Albums" and "My Photo Stream". You will find all images recently captured on your iPhone appear on the iPad. Choose the photo you want to save to iPad. Tap on the share button in the lower-left corner and then select "Save Image" and it is done.
Photo Stream offers impermanent storage for your photos. It only keeps the maximum 1000 pictures or the last 30 days of images. In addition, this service only works when Wi-Fi network is available. If you want to sync large number of pictures, iOS Transfer would be a great choice for you as it offers simple approach to easily sync iPhone images to iPad.