A prop is a prop as far as most rugby fans are concerned - but Alasdair Dickinson will aim this weekend to demonstrate the vast difference between playing loosehead and tighthead in the RBS 6 Nations.
The Gloucester forward will don the Scotland number one jersey for the first time since his debut almost a year and a half ago when Grand Slam-chasing Ireland arrive at Murrayfield on Saturday.
Seventeen-stone Dickinson has spent the first three games of the Six Nations filling in at tighthead, coming off the bench against Wales and Italy, and starting in the position against France.
The 25-year-old, who left Edinburgh for Gloucester in 2007, played his part in a collective malaise in the tournament opener against Wales but his performances in the subsequent two matches were more than competent.
Yet, Dickinson is his own biggest critic, saying: "Tighthead was always going to be a massive struggle and I think I proved it was.
"I haven't performed very well in the last couple of games so I've definitely got a point to prove.
"I'm looking forward to this weekend. Loosehead's definitely more comfortable. At Gloucester, I'm not seen as a tighthead at all.
"When I went down there, they said, 'We want you to play loosehead', and I was happy with that.
"It's always difficult to go back playing tight - especially when I'm not 130 kilos.
"Loosehead's where I want to play and I have to go out there and prove it.
"It's still going to be a massive challenge but it's something I'll definitely look forward to."
Dundee-born Dickinson has been so unhappy with his contribution on the right-hand side of the scrum, it has even kept him awake at night.
"I take my rugby very seriously," he said. "I do take it personally and I pride myself on work ethic and I hate to lose.
"So, there's a few sleepless nights but hopefully we can rectify that this weekend."
Dickinson will make only his third Scotland start out of 12 caps this weekend and first at loosehead since the 40-0 World Cup thrashing by New Zealand.
He knows his first big opportunity to impress since that baptism of fire has only arrived because of an injury to Allan Jacobsen, who faces up to four months out after undergoing shoulder surgery.
"It's always bittersweet getting a start the way I am," Dickinson said.
"Allan was probably the in-form prop in the championship and I owe to him to go out and perform."
Playing loosehead will see Dickinson come up against one of the most grizzled campaigners in the game.
Saturday's match will be Ireland tighthead John Hayes' 93rd cap, seeing him overtake Malcolm O'Kelly as his country's appearance record holder.
Dickinson has faced the 35-year-old Munster stalwart before, both while at Edinburgh and Gloucester, but never on the international stage.
"He's very experienced and a very big man and it's going to be a massive challenge," Dickinson said. "He's 120-odd kilos and he'll be hard to shift."
Ireland arrive at Murrayfield looking to maintain their bid for a first Grand Slam since 1945, while Scotland will attempt to build on their first win of the tournament against Italy which was preceded by dispiriting defeats by Wales and France.
Dickinson said: "We've been working hard over the last month and sometimes you don't get the reward that you're after from the hard work you put in."
Peter O'Mahony was named man of the match against England last month
21 April 2017, 7:22pm
Peter O'Mahony's performance in the RBS 6 Nations finale for Ireland against England was crucial to his selection for the British & Irish Lions on Wednesday, Ireland and Lions defence coach Andy Farrell has revealed.