As you might well imagine, there are a host of variables at play here. However, some basic studies have indicated that, all other things being equal, a typical bout of strength (hypertrophy) training requires, at most, about half of the energy that is required of a similarly typical bout of endurance training. This can easily be confirmed by calculating and aggregating the total work performed in a strength-training session, and comparing it with work output estimates for an endurance session of the same duration.
The primary reason for this is that the loads involved in strength training are relatively difficult to move; that is, if we halve the load that we are lifting, we can do more than double the work. And consequently, our strength training bouts are necessarily punctuated by periods of rest, while our endurance sessions are typically continuous.
It is commonly stated that the additional muscle mass developed by strength training compensates for or even exceeds this disparity in energy usage, since an increase in muscle mass corresponds with an increase in our basal metabolic rate. However, this claim fails to account for the relatively small contribution that any increase in muscle mass has on basal metabolic rate. On average, skeletal muscle accounts for just 18% of the body's total metabolic activity. And men, who have an average of around 12 kilograms (26 pounds) more muscle mass and 36% greater strength (averaged across the upper and lower body) than women, have just 7-8% higher basal metabolic rates relative to their size.
Thus, the muscle developed from strength training, while significant, does not come close to compensating for the differences in energy usage in the two training modalities. It is worth noting, also, that endurance training also leads to hypertrophy and gains in strength.
The value of strength training should not be underestimated—ideally, regular endurance training would be combined with intermittent bouts of strength training. But in terms of energy consumption and fat loss, endurance training is far superior.