भविष्यति is in लृट् lakaara and भविता is in लुट् lakaara. Both are used to denote future tense, but there is a difference.
लृट् lakaara forms can be used for any future tense, including anything happening later today. For example: अद्य सायङ्काले कार्यक्रमः भविष्यति The programme happens today evening. श्वः कार्यक्रमः भविष्यति The programme happens tomorrow.
लुट् lakaara forms can be used for any future tense, from tomorrow onwards only. For example, श्वः कार्यक्रमः भविता The programme happens tomorrow.