import torch
import torch.nn as nn

pred   = torch.tensor([2.5, 0.5, 3.0])
target = torch.tensor([3.0, 0.0, 3.0])

print(nn.MSELoss()(pred, target))            # tensor(0.1667)
print(((pred - target) ** 2).mean())         # tensor(0.1667)