Answer:
Inference:
You want to find out what the effect of Age, Passenger Class and, Gender has on surviving the Titanic Disaster. You can put up a logistic regression and infer the effect each passenger characteristic has on survival rates.
Prediction:
Given some information on a Titanic passenger, you want to choose from the set {lives,dies}{lives,dies} and be correct as often as possible. (See bias-variance tradeoff for prediction in case you wonder how to be correct as often as possible.)